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Journal articles on the topic 'Radiolabeled peptide'

Author: Grafiati
Published: 14 March 2023

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1

Farzipour, Soghra, and Seyed Jalal Hosseinimehr. "Correlation between in vitro and in vivo Data of Radiolabeled Peptide for Tumor Targeting." Mini-Reviews in Medicinal Chemistry 19, no. 12 (July 12, 2019): 950–60. http://dx.doi.org/10.2174/1389557519666190304120011.

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Tumor-targeting peptides have been generally developed for the overexpression of tumor specific receptors in cancer cells. The use of specific radiolabeled peptide allows tumor visualization by single photon emission computed tomography (SPECT) and positron emission tomography (PET) tools. The high affinity and specific binding of radiolabeled peptide are focusing on tumoral receptors. The character of the peptide itself, in particular, its complex molecular structure and behaviors influence on its specific interaction with receptors which are overexpressed in tumor. This review summarizes various strategies which are applied for the expansion of radiolabeled peptides for tumor targeting based on in vitro and in vivo specific tumor data and then their data were compared to find any correlation between these experiments. With a careful look at previous studies, it can be found that in vitro unblock-block ratio was unable to correlate the tumor to muscle ratio and the success of radiolabeled peptide for in vivo tumor targeting. The introduction of modifiers’ approaches, nature of peptides, and type of chelators and co-ligands have mixed effect on the in vitro and in vivo specificity of radiolabeled peptides.
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2

Lo, Wei-Lin, Shih-Wei Lo, Su-Jung Chen, Ming-Wei Chen, Yuan-Ruei Huang, Liang-Cheng Chen, Chih-Hsien Chang, and Ming-Hsin Li. "Molecular Imaging and Preclinical Studies of Radiolabeled Long-Term RGD Peptides in U-87 MG Tumor-Bearing Mice." International Journal of Molecular Sciences 22, no. 11 (May 21, 2021): 5459. http://dx.doi.org/10.3390/ijms22115459.

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The Arg–Gly–Asp (RGD) peptide shows a high affinity for αvβ3 integrin, which is overexpressed in new tumor blood vessels and many types of tumor cells. The radiolabeled RGD peptide has been studied for cancer imaging and radionuclide therapy. We have developed a long-term tumor-targeting peptide DOTA-EB-cRGDfK, which combines a DOTA chelator, a truncated Evans blue dye (EB), a modified linker, and cRGDfK peptide. The aim of this study was to evaluate the potential of indium-111(111In) radiolabeled DOTA-EB-cRGDfK in αvβ3 integrin-expressing tumors. The human glioblastoma cell line U-87 MG was used to determine the in vitro binding affinity of the radiolabeled peptide. The in vivo distribution of radiolabeled peptides in U-87 MG xenografts was investigated by biodistribution, nanoSPECT/CT, pharmacokinetic and excretion studies. The in vitro competition assay showed that 111In-DOTA-EB-cRGDfK had a significant binding affinity to U-87 MG cancer cells (IC50 = 71.7 nM). NanoSPECT/CT imaging showed 111In-DOTA-EB-cRGDfK has higher tumor uptake than control peptides (111In-DOTA-cRGDfK and 111In-DOTA-EB), and there is still a clear signal until 72 h after injection. The biodistribution results showed significant tumor accumulation (27.1 ± 2.7% ID/g) and the tumor to non-tumor ratio was 22.85 at 24 h after injection. In addition, the pharmacokinetics results indicated that the 111In-DOTA-EB-cRGDfK peptide has a long-term half-life (T1/2λz = 77.3 h) and that the calculated absorbed dose was safe for humans. We demonstrated that radiolabeled DOTA-EB-cRGDfK may be a promising agent for glioblastoma tumor imaging and has the potential as a theranostic radiopharmaceutical.
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3

Persidis, A., A. A. Harcombe, A. P. Davenport, R. E. Kuc, C. Plumpton, and P. L. Weissberg. "Isolation of Human Cardiac Endothelin Receptors by a Peptide-Receptor Mobility Shift Assay." Clinical Science 85, no. 2 (August 1, 1993): 169–73. http://dx.doi.org/10.1042/cs0850169.

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1. A peptide-protein mobility shift assay has been developed, using native polyacrylamide-gel electrophoresis, that enables the isolation of de-natured receptor proteins from small amounts of human cardiac tissue. 2. Radiolabeled endothelin-1 and related peptides were used to identify and isolate endothelin receptors from partially purified membrane extracts of human atrial tissue. 3. Binding analysis using radiolabelled endothelin-1 gave an equilibrium dissociation constant (Kd) of 2 nmol/l, similar to results from binding experiments conducted directly on tissue. 4. Peptide-receptor complexes were electroeluted from native gels and dissociated. Receptor material was characterized by dot-immunobinding analysis of eluates using an antibody raised against a predicted human endothelin receptor sequence.
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4

Mansi, Rosalba, Berthold A. Nock, Simone U. Dalm, Martijn B. Busstra, Wytske M. van Weerden, and Theodosia Maina. "Radiolabeled Bombesin Analogs." Cancers 13, no. 22 (November 17, 2021): 5766. http://dx.doi.org/10.3390/cancers13225766.

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The gastrin-releasing peptide receptor (GRPR) is expressed in high numbers in a variety of human tumors, including the frequently occurring prostate and breast cancers, and therefore provides the rationale for directing diagnostic or therapeutic radionuclides on cancer lesions after administration of anti-GRPR peptide analogs. This concept has been initially explored with analogs of the frog 14-peptide bombesin, suitably modified at the N-terminus with a number of radiometal chelates. Radiotracers that were selected for clinical testing revealed inherent problems associated with these GRPR agonists, related to low metabolic stability, unfavorable abdominal accumulation, and adverse effects. A shift toward GRPR antagonists soon followed, with safer analogs becoming available, whereby, metabolic stability and background clearance issues were gradually improved. Clinical testing of three main major antagonist types led to promising outcomes, but at the same time brought to light several limitations of this concept, partly related to the variation of GRPR expression levels across cancer types, stages, previous treatments, and other factors. Currently, these parameters are being rigorously addressed by cell biologists, chemists, nuclear medicine physicians, and other discipline practitioners in a common effort to make available more effective and safe state-of-the-art molecular tools to combat GRPR-positive tumors. In the present review, we present the background, current status, and future perspectives of this endeavor.
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5

Zhang, Yifan, and Wengen Chen. "Radiolabeled glucagon-like peptide-1 analogues." Nuclear Medicine Communications 33, no. 3 (March 2012): 223–27. http://dx.doi.org/10.1097/mnm.0b013e32834e7f47.

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6

Zavvar, Taraneh Sadat, Anton Amadeus Hörmann, Maximilian Klingler, Dominik Summer, Christine Rangger, Laurence Desrues, Hélène Castel, Pierrick Gandolfo, and Elisabeth von Guggenberg. "Effects of Side Chain and Peptide Bond Modifications on the Targeting Properties of Stabilized Minigastrin Analogs." Pharmaceuticals 16, no. 2 (February 13, 2023): 278. http://dx.doi.org/10.3390/ph16020278.

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Different attempts have been made in the past two decades to develop radiolabeled peptide conjugates with enhanced pharmacokinetic properties in order to improve the application for tumor imaging and peptide receptor radionuclide therapy (PRRT), which targets the cholecystokinin-2 receptor (CCK2R). In this paper, the influence of different side chain and peptide bond modifications has been explored for the minigastrin analog DOTA-DGlu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1Nal-NH2 (DOTA-MGS5). Based on this lead structure, five new derivatives were synthesized for radiolabeling with trivalent radiometals. Different chemical and biological properties of the new derivatives were analyzed. Receptor interaction of the peptide derivatives and cell internalization of the radiolabeled peptides were studied in A431-CCK2R cells. The stability of the radiolabeled peptides in vivo was investigated using BALB/c mice. Tumor targeting of all 111In-labeled peptide conjugates, and of a selected compound radiolabeled with gallium-68 and lutetium-177, was evaluated in BALB/c nude mice xenografted with A431-CCK2R and A431-mock cells. All 111In-labeled conjugates, except [111In]In-DOTA-[Phe8]MGS5, showed a high resistance against enzymatic degradation. A high receptor affinity with IC50 values in the low nanomolar range was confirmed for most of the peptide derivatives. The specific cell internalization over time was 35.3–47.3% for all radiopeptides 4 h after incubation. Only [111In]In-DOTA-MGS5[NHCH3] exhibited a lower cell internalization of 6.6 ± 2.8%. An overall improved resistance against enzymatic degradation was confirmed in vivo. Of the radiopeptides studied, [111In]In-DOTA-[(N-Me)1Nal8]MGS5 showed the most promising targeting properties, with significantly increased accumulation of radioactivity in A431-CCK2R xenografts (48.1 ± 9.2% IA/g) and reduced accumulation of radioactivity in stomach (4.2 ± 0.5% IA/g). However, in comparison with DOTA-MGS5, a higher influence on the targeting properties was observed for the change of radiometal, resulting in a tumor uptake of 15.67 ± 2.21% IA/g for [68Ga]Ga-DOTA-[(N-Me)1Nal8]MGS5 and 35.13 ± 6.32% IA/g for [177Lu]Lu-DOTA-[(N-Me)1Nal8]MGS5.
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7

Ducharme, Maxwell, Hailey A. Houson, Solana R. Fernandez, and Suzanne E. Lapi. "Evaluation of 68Ga-Radiolabeled Peptides for HER2 PET Imaging." Diagnostics 12, no. 11 (November 5, 2022): 2710. http://dx.doi.org/10.3390/diagnostics12112710.

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One in eight women will be diagnosed with breast cancer in their lifetime and approximately 25% of those cases will be HER2-positive. Current methods for diagnosing HER2-positive breast cancer involve using IHC and FISH from suspected cancer biopsies to quantify HER2 expression. HER2 PET imaging could potentially increase accuracy and improve the diagnosis of lesions that are not available for biopsies. Using two previously discovered HER2-targeting peptides, we modified each peptide with the chelator DOTA and a PEG2 linker resulting in DOTA-PEG2-GSGKCCYSL (P5) and DOTA-PEG2-DTFPYLGWWNPNEYRY (P6). Each peptide was labeled with 68Ga and was evaluated for HER2 binding using in vitro cell studies and in vivo tumor xenograft models. Both [68Ga]P5 and [68Ga]P6 showed significant binding to HER2-positive BT474 cells versus HER2-negative MDA-MB-231 cells ([68Ga]P5; 0.68 ± 0.20 versus 0.47 ± 0.05 p < 0.05 and [68Ga]P6; 0.55 ± 0.21 versus 0.34 ± 0.12 p < 0.01). [68Ga]P5 showed a higher percent injected dose per gram (%ID/g) binding to HER2-positive tumors two hours post-injection compared to HER2-negative tumors (0.24 ± 0.04 versus 0.12 ± 0.06; p < 0.05), while the [68Ga]P6 peptide showed significant binding (0.98 ± 0.22 versus 0.51 ± 0.08; p < 0.05) one hour post-injection. These results lay the groundwork for the use of peptides to image HER2-positive breast cancer.
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8

Klingler, Maximilian, Anton Amadeus Hörmann, and Elisabeth Von Guggenberg. "Cholecystokinin-2 Receptor Targeting with Radiolabeled Peptides: Current Status and Future Directions." Current Medicinal Chemistry 27, no. 41 (December 8, 2020): 7112–32. http://dx.doi.org/10.2174/0929867327666200625143035.

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A wide variety of radiolabeled peptide analogs for specific targeting of cholecystokinin- 2 receptors (CCK2R) has been developed in the last decades. Peptide probes based on the natural ligands Minigastrin (MG) and Cholecystokinin (CCK) have a high potential for molecular imaging and targeted radiotherapy of different human tumors, such as Medullary Thyroid Carcinoma (MTC) and Small Cell Lung Cancer (SCLC). MG analogs with high persistent uptake in CCK2R expressing tumors have been preferably used for the development of radiolabeled peptide analogs. The clinical translation of CCK2R targeting has been prevented due to high kidney uptake or low metabolic stability of the different radiopeptides developed. Great efforts in radiopharmaceutical development have been undertaken to overcome these limitations. Various modifications in the linear peptide sequence of MG have been introduced mainly with the aim to reduce kidney retention. Furthermore, improved tumor uptake could be obtained by in situ stabilization of the radiopeptide against enzymatic degradation through coinjection of peptidase inhibitors. Recent developments focusing on the stabilization of the Cterminal receptor binding sequence (Trp-Met-Asp-Phe-NH2) have led to new radiolabeled MG analogs with highly improved tumor uptake and tumor-to-kidney ratio. In this review, all the different aspects in the radiopharmaceutical development of CCK2R targeting peptide probes are covered, giving also an overview on the clinical investigations performed so far. The recent development of radiolabeled MG analogs, which are highly stabilized against enzymatic degradation in vivo, promises to have a high impact on the clinical management of patients with CCK2R expressing tumors in the near future.
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9

Şenışık, Ahmet M., Çiğdem İçhedef, Ayfer Y. Kılçar, Eser Uçar, Kadir Arı, Yasemin Parlak, Elvan S. Bilgin, and Serap Teksöz. "Evaluation of New 99mTc(CO)3 + Radiolabeled Glycylglycine In Vivo." Anti-Cancer Agents in Medicinal Chemistry 19, no. 11 (October 17, 2019): 1382–87. http://dx.doi.org/10.2174/1871520619666190404154723.

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Background: Peptide-based agents are used in molecular imaging due to their unique properties, such as rapid clearance from the circulation, high affinity and target selectivity. Many of the radiolabeled peptides have been clinically experienced with diagnostic accuracy. The aim of this study was to investigate in vivo biological behavior of [99mTc(CO)3(H2O)3]+ radiolabeled glycylglycine (GlyGly). Methods: Glycylglycine was radiolabeled with a high radiolabeling yield of 94.69±2%, and quality control of the radiolabeling process was performed by thin layer radiochromatography (TLRC) and High-Performance Liquid Radiochromatography (HPLRC). Lipophilicity study for radiolabeled complex (99mTc(CO)3-Gly-Gly) was carried out using solvent extraction. The in vivo evaluation was performed by both biodistribution and SPECT imaging. Results: The high radiolabelling yield of 99mTc(CO)3-GlyGly was obtained and verified by TLRC and HPLRC as well. According to the in vivo results, SPECT images and biodistribution data are in good accordance. The excretion route from the body was both hepatobiliary and renal. Conclusion: This study shows that 99mTc(CO)3-GlyGly has the potential to be used as a peptide-based imaging agent. Further studies, 99mTc(CO)3-GlyGly can be performed on tumor-bearing animals.
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10

Mansi, Rosalba, and Melpomeni Fani. "Radiolabeled Peptides for Cancer Imaging and Therapy: From Bench-to-Bedside." CHIMIA International Journal for Chemistry 75, no. 6 (June 30, 2021): 500–504. http://dx.doi.org/10.2533/chimia.2021.500.

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Radiolabeled peptides can deliver radiation selectively to tumors via targeting peptide receptors that are overexpressed on the surface of cancer cells. The radiation is used either for detection (imaging) or for destruction (therapy) of these tumors. The Division of Radiopharmaceutical Chemistry at the University Hospital Basel has conducted pioneering work on the development of peptide-based radiopharmaceuticals. Our research covers the entire spectrum of such developments, from bench-to-bedside, and it is illustrated in this article by selective cases.
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11

Huynh, Truc Thao, Sreeja Sreekumar, Cedric Mpoy, and Buck Edward Rogers. "Therapeutic Efficacy of 177Lu-Labeled A20FMDV2 Peptides Targeting ανβ6." Pharmaceuticals 15, no. 2 (February 15, 2022): 229. http://dx.doi.org/10.3390/ph15020229.

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Integrin ανβ6 promotes migration and invasion of cancer cells, and its overexpression often correlates with poor survival. Therefore, targeting ανβ6 with radioactive peptides would be beneficial for cancer imaging and therapy. Previous studies have successfully developed radiotracers based on the peptide A20FMDV2 that showed good binding specificity for ανβ6. However, one concern of these ανβ6 integrin-targeting probes is that their rapid blood clearance and low tumor uptake would preclude them from being used for therapeutic purposes. In this study, albumin binders were used to increase tumor uptake for therapeutic applications while the non-albumin peptide was evaluated as a potential positron emission tomography (PET) imaging agent. All peptides used the DOTA chelator for radiolabeling with either 68Ga for imaging or 177Lu for therapy. PET imaging with [68Ga]Ga-DOTA-(PEG28)2-A20FMDV2 revealed specific tumor uptake in ανβ6-positive tumors. Albumin-binding peptides EB-DOTA-(PEG28)2-A20FMDV2 and IBA-DOTA-(PEG28)2-A20FMDV2 were radiolabeled with 177Lu. Biodistribution studies in normal mice showed longer blood circulation times for the albumin binding peptides compared to the non-albumin peptide. Therapy studies in mice demonstrated that both 177Lu-labeled albumin binding peptides resulted in significant tumor growth inhibition. We believe these are the first studies to demonstrate the therapeutic efficacy of a radiolabeled peptide targeting an ανβ6-positive tumor.
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12

Cao, Rui, Hongguang Liu, and Zhen Cheng. "Radiolabeled Peptide Probes for Liver Cancer Imaging." Current Medicinal Chemistry 27, no. 41 (December 8, 2020): 6968–86. http://dx.doi.org/10.2174/0929867327666200320153837.

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Liver cancer/Hepatocellular Carcinoma (HCC) is a leading cause of cancer death and represents an important cause of mortality worldwide. Several biomarkers are overexpressed in liver cancer, such as Glypican 3 (GPC3) and Epidermal Growth Factor Receptor (EGFR). These biomarkers play important roles in the progression of tumors and could serve as imaging and therapeutic targets for this disease. Peptides with adequate stability, receptor binding properties, and biokinetic behavior have been intensively studied for liver cancer imaging. A great variety of them have been radiolabeled with clinically relevant radionuclides for liver cancer diagnosis, and many are promising imaging and therapeutic candidates for clinical translation. Herein, we summarize the advancement of radiolabeled peptides for the targeted imaging of liver cancer.
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13

Ruzza, Paolo, and Andrea Calderan. "Radiolabeled peptide-receptor ligands in tumor imaging." Expert Opinion on Medical Diagnostics 5, no. 5 (June 15, 2011): 411–24. http://dx.doi.org/10.1517/17530059.2011.592829.

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14

de Oliveira, Érica Aparecida, Bluma Linkowski Faintuch, Daniele Seo, Angélica Bueno Barbezan, Ana Funari, Roselaine Campos Targino, and Ana Maria Moro. "Radiolabeled GX1 Peptide for Tumor Angiogenesis Imaging." Applied Biochemistry and Biotechnology 185, no. 4 (January 24, 2018): 863–74. http://dx.doi.org/10.1007/s12010-018-2700-z.

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15

Aligholikhamseh, Nazan, Sajjad Ahmadpour, Fatemeh Khodadust, Seyed Mohammad Abedi, and Seyed Jalal Hosseinimehr. "99mTc-HYNIC-(Ser)3-LTVPWY peptide bearing tricine as co-ligand for targeting and imaging of HER2 overexpression tumor." Radiochimica Acta 106, no. 7 (July 26, 2018): 601–9. http://dx.doi.org/10.1515/ract-2017-2868.

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Abstract Human epidermal growth factor receptor 2 (HER2) is overexpressed in several cancers. Today’s tumor targeting is receiving more attention due to its specificity to target receptor-dependent cancers. The aim of this study was to evaluate the 99mTc-HYNIC-(tricine)-(Ser)3-LTVPWY peptide for tumor targeting and imaging with overexpression of HER2. HYNIC-(Ser)3-LTVPWY peptide was labeled with 99mTc using tricine as a co-ligand at room temperature. Specific binding of this radiolabeled peptide was assessed on four cancer cell lines with different levels of HER2 receptor expression. Also the affinity of 99mTc-HYNIC-(tricine)-(Ser)3-LTVPWY peptide to the HER2 receptor was evaluated in the SKOV-3 cell line. Biodistribution study of this radiolabeled peptide was performed in SKOV-3 tumor bearing nude mice. The HYNIC conjugated peptide was simply labeled with 99mTc radionuclide with high labeling efficiency about 98±1% showing favorable stability in normal saline and human serum. In the presence of unlabeled peptide as competitor, the HER2 binding capacity of the radiolabeled peptide reduced (approximately five-fold). The KD and Bmax values were found 2.6±0.5 nM and (2.6±0.1)×106, respectively. The tumor/muscle ratios for this radiotracer were determined 1.17±0.77, 1.15±0.32 and 2.65±0.32 at 1, 2 and 4 h after injection, respectively. Presaturation of HER2 receptors in SKOV-3 xenografted nude mice showed a reduction in the tumor/muscle ratio confirming in vivo specificity of the peptide. According to SPECT imaging, the tumor was visualized in mouse after 4 h postinjection of radiolabeled peptide. 99mTc-HYNIC-(tricine)-(Ser)3-LTVPWY peptide exhibited overexpressed HER2 tumor targeting.
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16

Judmann, Benedikt, Diana Braun, Björn Wängler, Ralf Schirrmacher, Gert Fricker, and Carmen Wängler. "Current State of Radiolabeled Heterobivalent Peptidic Ligands in Tumor Imaging and Therapy." Pharmaceuticals 13, no. 8 (July 30, 2020): 173. http://dx.doi.org/10.3390/ph13080173.

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Over the past few years, an approach emerged that combines different receptor-specific peptide radioligands able to bind different target structures on tumor cells concomitantly or separately. The reason for the growing interest in this special field of radiopharmaceutical development is rooted in the fact that bispecific peptide heterodimers can exhibit a strongly increased target cell avidity and specificity compared to their corresponding monospecific counterparts by being able to bind to two different target structures that are overexpressed on the cell surface of several malignancies. This increase of avidity is most pronounced in the case of concomitant binding of both peptides to their respective targets but is also observed in cases of heterogeneously expressed receptors within a tumor entity. Furthermore, the application of a radiolabeled heterobivalent agent can solve the ubiquitous problem of limited tumor visualization sensitivity caused by differential receptor expression on different tumor lesions. In this article, the concept of heterobivalent targeting and the general advantages of using radiolabeled bispecific peptidic ligands for tumor imaging or therapy as well as the influence of molecular design and the receptors on the tumor cell surface are explained, and an overview is given of the radiolabeled heterobivalent peptides described thus far.
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17

Ojcius, D. M., J. P. Abastado, A. Casrouge, E. Mottez, L. Cabanie, and P. Kourilsky. "Dissociation of the peptide-MHC class I complex limits the binding rate of exogenous peptide." Journal of Immunology 151, no. 11 (December 1, 1993): 6020–26. http://dx.doi.org/10.4049/jimmunol.151.11.6020.

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Abstract Soluble, single-chain molecules for two MHC class I alleles, H-2Kd and H-2Kb, were used to analyze the kinetics of antigenic peptide binding to MHC. After MHC preloading with radiolabeled or fluorescent peptides, the observed rate of MHC-peptide complex dissociation increased after addition of an excess of unlabeled competitor peptide. Although exogenous peptides conforming to the allele-specific motif were required for the enhanced complex dissociation to occur, the dissociation rate of the complex was independent of exogenous peptide concentration. Similarly, the association rate of exogenous peptides was independent of concentration, reflecting the presence of low affinity peptides in the binding sites of the recombinant MHC proteins; the sequences of these endogenous peptides conform to the consensus motif for the MHC allele studied. Finally, the association rate of exogenous peptide decreased when MHC molecules were preloaded with high affinity peptides, and the binding of labeled high affinity peptide to isolated recombinant MHC was faster than the subsequent dissociation observed in the presence of competitor peptide. Taken together, these results imply that the rate of exogenous peptide binding is limited by the dissociation rate of the previously bound peptides.
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18

del Guercio, M. F., J. Sidney, G. Hermanson, C. Perez, H. M. Grey, R. T. Kubo, and A. Sette. "Binding of a peptide antigen to multiple HLA alleles allows definition of an A2-like supertype." Journal of Immunology 154, no. 2 (January 15, 1995): 685–93. http://dx.doi.org/10.4049/jimmunol.154.2.685.

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Abstract Direct MHC binding assays with radiolabeled peptides and HLA class I-expressing mammalian cells such as EBV-transformed B cell lines and PHA-activated blasts have been developed. Significant binding of the radiolabeled probe could be obtained if the target cells were preincubated overnight at 26 degrees C in the presence of beta 2-microglobulin. Under these conditions, up to a few percent of the HLA molecules expressed by either cell type could be bound by the labeled peptides. With these assays, the degree of cross-reactivity of the A*0201-restricted hepatitis B virus core 18-27 peptide with other A2 subtypes was examined. It was determined that this peptide epitope also binds the A*0202, A*0205, and A*0206 but not A*0207 subtypes. Inhibition experiments with panels of synthetic peptide analogues underlined the similar ligand specificities of the HLA-A*0201, A*0202, and A*0205 alleles. Analysis of the polymorphic residues that help form the B and F pockets of various HLA alleles allowed prediction of binding of the hepatitis B virus core 18-27 epitope to two other HLA alleles (HLA-A*6802 and A*6901). Thus, it appears that a family of at least six different HLA-A molecules may share overlapping ligand specificities (aliphatic residues in position 2 and at the C termini). These results suggest that broadly cross-reactive peptide epitopes can be identified and greatly enhance the prospective feasibility of peptide-based vaccination approaches.
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19

Aweda, Tolulope A., Zumrut F. B. Muftuler, Adriana V. F. Massicano, Dhruval Gadhia, Kelly A. McCarthy, Stacy Queern, Anupam Bandyopadhyay, Jianmin Gao, and Suzanne E. Lapi. "Radiolabeled Cationic Peptides for Targeted Imaging of Infection." Contrast Media & Molecular Imaging 2019 (October 29, 2019): 1–11. http://dx.doi.org/10.1155/2019/3149249.

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Molecular probes targeting bacteria provide opportunities to target bacterial infections in vivo for both imaging and therapy. In the current study, we report the development of positron emission tomography (PET) probes for imaging of live bacterial infection based on the small molecules HLys-DOTA, a polycationic peptide synthesized as the D-isomer (RYWVAWRNRG) conjugated to 1, 4, 7, 10-tetraazacyclododecane-N′,N″,N‴,N-tetraacetic acid (DOTA) and AB1-HLys-DOTA, which includes an unnatural amino acid AB1 that preferentially binds to bacteria membrane lipids with amine groups via formation of iminoboronates. HLys-DOTA and AB1-HLys-DOTA peptides were radiolabeled with 64Cu and investigated as PET imaging agents to track bacterial infection in vitro and in intramuscularly infected (IM) mice models. Cell uptake studies at 37°C in Staphylococcus aureus (SA) show higher uptake of 64Cu-AB1-HLys-DOTA; 98.47 ± 3.54% vs 64Cu-HLys-DOTA; 39.12 ± 3.27% at 24 h. Standard uptake values (SUV) analysis of the PET images resulted in mean SUV of 0.70 ± 0.08, 0.49 ± 0.04, and 0.31 ± 0.01 for 64Cu-AB1-HLys-DOTA and 0.17 ± 0.06, 0.16 ± 0.02, and 0.13 ± 0.01 for 64Cu-HLys-DOTA at 1, 4, and 24 h post injection, respectively, in the infected muscles. Similarly, in the biodistribution studies, dose uptake in the infected muscles was 4 times higher in the targeted 64Cu-AB1-HLys-DOTA group than in the 64Cu-HLys-DOTA group and 2‐3 times higher than in the PBS control group at 1, 4, and 24 h post injection. 64Cu-AB1-HLys-DOTA was able to distinguish between SA-infected muscle and Pseudomonas aeruginosa (PA) infected muscle with lower mean SUV of 0.28 ± 0.10 at 1 h post injection. This illustrates the utility of the AB1 covalently targeting group in synergy with the HLys peptide, which noncovalently binds to bacterial membranes. These results suggest that 64Cu-labeled AB1-HLys-DOTA peptide could be used as an imaging probe for detection of bacterial infection in vivo with specificity for Gram-positive bacteria.
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20

Helbok, Anna, Christine Rangger, Elisabeth von Guggenberg, Matthias Saba-Lepek, Thorsten Radolf, Gudrun Thurner, Fritz Andreae, Ruth Prassl, and Clemens Decristoforo. "Targeting properties of peptide-modified radiolabeled liposomal nanoparticles." Nanomedicine: Nanotechnology, Biology and Medicine 8, no. 1 (January 2012): 112–18. http://dx.doi.org/10.1016/j.nano.2011.04.012.

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21

Knight, Linda C. "Radiolabeled peptide ligands for imaging thrombi and emboli." Nuclear Medicine and Biology 28, no. 5 (July 2001): 515–26. http://dx.doi.org/10.1016/s0969-8051(01)00222-0.

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22

Rohren, E. M., L. R. Pease, H. L. Ploegh, and T. N. Schumacher. "Polymorphisms in pockets of major histocompatibility complex class I molecules influence peptide preference." Journal of Experimental Medicine 177, no. 6 (June 1, 1993): 1713–21. http://dx.doi.org/10.1084/jem.177.6.1713.

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The set of peptides that is bound by a given major histocompatibility complex class I product can be described by one or two properly spaced anchor residues, and two properly spaced peptide termini, approximately 8-10 residues apart. Using radiolabeled peptide libraries, we examined whether mutations in those "pockets" in class I Kb molecules that do not seem critically involved in the interaction with the peptide anchor residues, do exert an effect on the set of preferred peptides. We find that mutations in all the pockets found in the structure of Kb have a significant effect on the peptide preference of the molecule, and their recognition by cytotoxic T cells. Alterations in substrate specificity are also observed for mutations involving residues that interact with main chain atoms in both peptide termini. These findings challenge a static view of the interaction of peptide termini with their respective pockets in the class I molecule, and imply a role for the minor pockets in peptide selectivity.
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23

Neisig, A., J. Roelse, A. J. Sijts, F. Ossendorp, M. C. Feltkamp, W. M. Kast, C. J. Melief, and J. J. Neefjes. "Major differences in transporter associated with antigen presentation (TAP)-dependent translocation of MHC class I-presentable peptides and the effect of flanking sequences." Journal of Immunology 154, no. 3 (February 1, 1995): 1273–79. http://dx.doi.org/10.4049/jimmunol.154.3.1273.

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Abstract The MHC-encoded transporter associated with Ag presentation (TAP) translocates peptides from the cytosol to the ER lumen, where association with MHC class I molecules occurs. The MHC class I/peptide complex is subsequently transported to the cell surface for presentation to CD8+T cells. We studied TAP-dependent translocation of defined MHC class I presentable murine peptides by competition for translocation of a radiolabeled model peptide, to address whether efficient peptide presentation by MHC class I molecules is preceded by equal efficient peptide translocation by TAP. Surprisingly, we observed that four immunodominant viral peptides of 16 peptides tested were very inefficiently transported by TAP. Inefficient translocation could be overcome by substitution of a proline residue present at position 3 in the peptides. Furthermore, addition of natural flanking amino acids directly surrounding a poorly transported peptide could considerably improve translocation by TAP. Our data suggest that some peptides are efficiently transported by TAP in their optimal size for MHC class I binding, whereas other peptides are transported as larger peptide fragments that need further trimming in the ER for MHC class I binding.
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24

Black, Kvar C. L., Walter J. Akers, Gail Sudlow, Baogang Xu, Richard Laforest, and Samuel Achilefu. "Dual-radiolabeled nanoparticle SPECT probes for bioimaging." Nanoscale 7, no. 2 (2015): 440–44. http://dx.doi.org/10.1039/c4nr05269b.

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25

Momburg, F., J. Roelse, G. J. Hämmerling, and J. J. Neefjes. "Peptide size selection by the major histocompatibility complex-encoded peptide transporter." Journal of Experimental Medicine 179, no. 5 (May 1, 1994): 1613–23. http://dx.doi.org/10.1084/jem.179.5.1613.

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The major histocompatibility complex (MHC)-encoded heterodimeric TAP1/TAP2 transporter (TAP) translocates cytosolic peptides into the lumen of the endoplasmic reticulum (ER), where peptides of 8 to 11 amino acids long associate with MHC class I molecules. We have studied the selectivity of peptide translocation by TAP in streptolysin O-permeabilized cells using glycosylatable, radioiodinated model peptides to detect import into the ER lumen. TAP-dependent translocation of a radiolabeled nonamer peptide was most efficiently inhibited by unlabeled 9- to 11-mer peptides. Peptides between 7 and 40 amino acids long all could inhibit transport, the longer peptides being least effective. Also, peptides shorter than eight amino acids were inefficiently translocated. The use of directly labeled length variants in translocation assays and TLC analysis of the transported material revealed two pathways for translocation: short peptides (7 to 13 amino acids long) were translocated without prior modification. In contrast, transport of longer peptides was not effective. Instead such peptides were clipped by cytosolic peptidases before efficient transport. Our data suggest that TAP preferentially translocates peptides of appropriate length for class I binding. Furthermore, TAP-translocated peptides were rapidly released from the ER unless they were trapped there by being glycosylated or by binding to MHC class I molecules.
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26

Huynh, Truc T., Ellen M. van Dam, Sreeja Sreekumar, Cedric Mpoy, Benjamin J. Blyth, Fenella Muntz, Matthew J. Harris, and Buck E. Rogers. "Copper-67-Labeled Bombesin Peptide for Targeted Radionuclide Therapy of Prostate Cancer." Pharmaceuticals 15, no. 6 (June 8, 2022): 728. http://dx.doi.org/10.3390/ph15060728.

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The gastrin-releasing peptide receptor (GRPR) is a promising molecular target for imaging and therapy of prostate cancer using bombesin peptides that bind to the receptor with high affinity. Targeted copper theranostics (TCTs) using copper radionuclides, 64Cu for imaging and 67Cu for therapy, offer significant advantages in the development of next-generation theranostics. [64Cu]Cu-SAR-BBN is in clinical development for PET imaging of GRPR-expressing cancers. This study explores the therapeutic efficacy of [67Cu]Cu-SAR-BBN in a pre-clinical mouse model. The peptide was radiolabeled with 67Cu, and specific binding of the radiolabeled peptide towards GRPR-positive PC-3 prostate cancer cells was confirmed with 52.2 ± 1.4% total bound compared to 5.8 ± 0.1% with blocking. A therapy study with [67Cu]Cu-SAR-BBN was conducted in mice bearing PC-3 tumors by injecting 24 MBq doses a total of six times. Tumor growth was inhibited by 93.3% compared to the control group on day 19, and median survival increased from 34.5 days for the control group to greater than 54 days for the treatment group. The ease and stability of the radiochemistry, favorable biodistribution, and the positive tumor inhibition demonstrate the suitability of this copper-based theranostic agent for clinical assessment in the treatment of cancers expressing GRPR.
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27

Faintuch, B. L., E. A. Oliveira, R. C. Targino, and A. M. Moro. "Radiolabeled NGR phage display peptide sequence for tumor targeting." Applied Radiation and Isotopes 86 (April 2014): 41–45. http://dx.doi.org/10.1016/j.apradiso.2013.12.035.

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28

Miyamoto, Y., V. Ganapathy, A. Barlas, K. Neubert, A. Barth, and F. H. Leibach. "Role of dipeptidyl peptidase IV in uptake of peptide nitrogen from beta-casomorphin in rabbit renal BBMV." American Journal of Physiology-Renal Physiology 252, no. 4 (April 1, 1987): F670—F677. http://dx.doi.org/10.1152/ajprenal.1987.252.4.f670.

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We examined the handling of radiolabeled beta-casomorphin, Tyr-Pro-[3H]Phe-Pro-Gly, by rabbit renal brush-border membrane vesicles (BBMV). The uptake of radiolabel into the vesicles was Na+-independent, but an inward-directed H+ gradient stimulated the uptake. The H+ gradient-dependent uptake was further accelerated by an interior-negative membrane potential, but inhibited in the presence of a protonophore. Treatment of the membrane vesicles with diisopropylfluorophosphate (DFP) greatly reduced the uptake of the radiolabel. Control as well as DFP-treated vesicles exhibited H+ gradient-dependent Gly-Sar uptake. Unlabeled beta-casomorphin inhibited Gly-Sar uptake in control vesicles, but the inhibition was significantly reduced in DFP-treated vesicles. DFP inhibited the activity of dipeptidyl peptidase IV in these vesicles and there was a direct correlation between the activity of the enzyme and the capacity of beta-casomorphin to inhibit Gly-Sar uptake. Many di- and tripeptides reduced the uptake of Gly-Sar and the uptake of radiolabel from beta-[3H]casomorphin to a similar extent. We conclude that beta-casomorphin is hydrolyzed by dipeptidyl peptidase IV and the products are transported into the vesicles by the H+ gradient-driven peptide transport system. This conclusion is supported by the results from the analysis of the incubation medium by high-performance liquid chromatography that showed rapid hydrolysis of the pentapeptide by brush-border membranes to di- and tripeptides.
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29

Briganti, Vittorio, Vincenzo Cuccurullo, Giuseppe Danilo Di Stasio, and Luigi Mansi. "Gamma Emitters in Pancreatic Endocrine Tumors Imaging in the PET Era: Is there a Clinical Space for 99mTc-peptides?" Current Radiopharmaceuticals 12, no. 2 (July 16, 2019): 156–70. http://dx.doi.org/10.2174/1874471012666190301122524.

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Background: Pancreatic Neuroendocrine Tumors (PNETs) are rare neoplasms, sporadic or familial, even being part of a syndrome. Their diagnosis is based on symptoms, hormonal disorders or may be fortuitous. The role of Nuclear Medicine is important, mainly because of the possibility of a theranostic strategy. This approach is allowed by the availability of biochemical agents, which may be labeled with radionuclides suitable for diagnostic or therapeutic purposes, showing almost identical pharmacokinetics. The major role for radiopharmaceuticals is connected with radiolabeled Somatostatin Analogues (SSA), since somatostatin receptors are highly expressed on some of the neoplastic cell types. Discussion: Nowadays, in the category of radiolabeled SSA, although 111In-pentetreotide, firstly commercially proposed, is still used, the best choice for diagnosis is related to the so called DOTAPET radiotracers labeled with 68-Gallium (Ga), such as 68Ga-DOTATATE, 68Ga-DOTANOC, and 68Ga-DOTATOC. More recently, labeling with 64-Copper (Cu) (64Cu-DOTATATE) has also been proposed. In this review, we discuss the clinical interest of a SAA (Tektrotyd©) radiolabeled with 99mTc, a gamma emitter with better characteristics, with respect to 111Indium, radiolabeling Octreoscan ©. By comparing both pharmacokinetics and pharmacodynamics of Octreoscan©, Tektrotyd© and PET DOTA-peptides, on the basis of literature data and of our own experience, we tried to highlight these topics to stimulate further studies, individuating actual clinical indications for all of these radiotracers. Conclusion: In our opinion, Tektrotyd© could already find its applicative dimension in the daily practice of NETs, either pancreatic or not, at least in centers without a PET/CT or a 68Ga generator. Because of wider availability, a lower cost, and a longer decay, compared with respect to peptides labeled with 68Ga, it could be also proposed, in a theranostic context, for a dosimetry evaluation of patients undergoing Peptide Receptor Radionuclide Therapy (PRRT), and for non-oncologic indications of radiolabelled SSA. In this direction, and for a more rigorous cost/effective evaluation, more precisely individuating its clinical role, further studies are needed.
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30

Farahani, Arezou M., Fariba Maleki, and Nourollah Sadeghzadeh. "The Influence of Different Spacers on Biological Profile of Peptide Radiopharmaceuticals for Diagnosis and Therapy of Human Cancers." Anti-Cancer Agents in Medicinal Chemistry 20, no. 4 (May 15, 2020): 402–16. http://dx.doi.org/10.2174/1871520620666191231161227.

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Background: Cancer is the leading cause of death worldwide. Early detection can reduce the disadvantageous effects of diseases and the mortality in cancer. Nuclear medicine is a powerful tool that has the ability to diagnose malignancy without harming normal tissues. In recent years, radiolabeled peptides have been investigated as potent agents for cancer detection. Therefore, it is necessary to modify radiopeptides in order to achieve more effective agents. Objective: This review describes modifications in the structure of radioconjugates with spacers who have improved the specificity and sensitivity of the peptides that are used in oncologic diagnosis and therapy. Methods: To improve the biological activity, researchers have conjugated these peptide analogs to different spacers and bifunctional chelators. Many spacers of different kinds, such as hydrocarbon chain, amino acid sequence, and poly (ethyleneglycol) were introduced in order to modify the pharmacokinetic properties of these biomolecules. Results: Different spacers have been applied to develop radiolabeled peptides as potential tracers in nuclear medicine. Spacers with different charge and hydrophilicity affect the characteristics of peptide conjugate. For example, the complex with uncharged and hydrophobic spacers leads to increased liver uptake, while the composition with positively charged spacers results in high kidney retention. Therefore, the pharmacokinetics of radio complexes correlates to the structure and total charge of the conjugates. Conclusion: Radio imaging technology has been successfully applied to detect a tumor in the earliest stage. For this purpose, the assessment of useful agents to diagnose the lesion is necessary. Developing peptide radiopharmaceuticals using spacers can improve in vitro and in vivo behavior of radiotracers leading to better noninvasive detection and monitoring of tumor growth.
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31

Haverstick, DM, JF Cowan, KM Yamada, and SA Santoro. "Inhibition of platelet adhesion to fibronectin, fibrinogen, and von Willebrand factor substrates by a synthetic tetrapeptide derived from the cell-binding domain of fibronectin." Blood 66, no. 4 (October 1, 1985): 946–52. http://dx.doi.org/10.1182/blood.v66.4.946.946.

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Abstract The role in platelet function of the cell-binding region of fibronectin was explored by the use of synthetic peptides. The prototypical peptide gly-arg-gly-asp-ser was capable of inhibiting thrombin-induced platelet aggregation without altering the degree of platelet activation as judged by the secretion of 14C-serotonin. The peptide also effectively inhibited, in a concentration-dependent manner, the binding of radiolabeled fibronectin to platelets and the adhesion of platelets to fibronectin substrates. The smallest peptide from the cell-binding region of fibronectin which retained full activity was arg-gly-asp-ser. Transposition of amino acids or conservative substitutions of amino acids within this short sequence resulted in inactive peptides. Peptides containing the arg-gly-asp-ser sequence were also capable of inhibiting the adhesion of platelets to fibrinogen and von Willebrand factor substrates. Examination of the entire panel of synthetic peptides for ability to inhibit adhesion to fibrinogen or von Willebrand factor substrates revealed the same structure-function relationships that had been determined in the studies with fibronectin.
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32

Haverstick, DM, JF Cowan, KM Yamada, and SA Santoro. "Inhibition of platelet adhesion to fibronectin, fibrinogen, and von Willebrand factor substrates by a synthetic tetrapeptide derived from the cell-binding domain of fibronectin." Blood 66, no. 4 (October 1, 1985): 946–52. http://dx.doi.org/10.1182/blood.v66.4.946.bloodjournal664946.

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The role in platelet function of the cell-binding region of fibronectin was explored by the use of synthetic peptides. The prototypical peptide gly-arg-gly-asp-ser was capable of inhibiting thrombin-induced platelet aggregation without altering the degree of platelet activation as judged by the secretion of 14C-serotonin. The peptide also effectively inhibited, in a concentration-dependent manner, the binding of radiolabeled fibronectin to platelets and the adhesion of platelets to fibronectin substrates. The smallest peptide from the cell-binding region of fibronectin which retained full activity was arg-gly-asp-ser. Transposition of amino acids or conservative substitutions of amino acids within this short sequence resulted in inactive peptides. Peptides containing the arg-gly-asp-ser sequence were also capable of inhibiting the adhesion of platelets to fibrinogen and von Willebrand factor substrates. Examination of the entire panel of synthetic peptides for ability to inhibit adhesion to fibrinogen or von Willebrand factor substrates revealed the same structure-function relationships that had been determined in the studies with fibronectin.
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33

Silver, P., I. Sadler, and M. A. Osborne. "Yeast proteins that recognize nuclear localization sequences." Journal of Cell Biology 109, no. 3 (September 1, 1989): 983–89. http://dx.doi.org/10.1083/jcb.109.3.983.

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A variety of peptides can mediate the localization of proteins to the nucleus. We have identified yeast proteins of 70 and 59 kD that bind to nuclear localization peptides of SV-40 T antigen, Xenopus nucleoplasmin, and the yeast proteins Ga14 and histone H2B. These proteins are assayed by the binding of peptide-albumin conjugates to proteins immobilized on nitrocellulose filters. These binding proteins fractionate with nuclei and are extractable with salt but not detergent. Radiolabeled peptide-albumin conjugates also bind to isolated nuclei; the binding is saturable and can be extracted with salt. Different nuclear localization peptides compete with each other, implying that a single class of proteins is responsible for their recognition. The 70- and 59-kD proteins have the properties expected for a receptor that would act to direct proteins to the nucleus.
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34

Hosseinimehr, Seyed Jalal, Vladimir Tolmachev, and Anna Orlova. "Liver uptake of radiolabeled targeting proteins and peptides: considerations for targeting peptide conjugate design." Drug Discovery Today 17, no. 21-22 (November 2012): 1224–32. http://dx.doi.org/10.1016/j.drudis.2012.07.002.

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35

Kaur, Jasleen, Karim Arroub, Alexander Drzezga, Klaus Schomäcker, and Sanjay Mathur. "Synthesis, proteolytic stability, and in vitro evaluation of DOTA conjugated p160 peptide based radioconjugates: [177Lu]Lu–DOTA–p160." Organic & Biomolecular Chemistry 19, no. 45 (2021): 9849–54. http://dx.doi.org/10.1039/d1ob01812d.

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Synthesis, spectroscopic characterization, and in vitro biological evaluation of Lu-177 radiolabeled DOTA conjugated p160 peptide derivatives: potential candidates for breast tumor imaging and therapy.
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36

Goldenberg, David M., Robert M. Sharkey, Habibe Karacay, Chien-Hsing Chang, Edmund A. Rossi, and William J. McBride. "Improved Responses and Cures with Less Hematologic Toxicity Using Anti-CD20 Bispecific Antibody Pretargeted Radionuclides Compared to Directly Radiolabeled IgG in a NHL Model." Blood 110, no. 11 (November 16, 2007): 2344. http://dx.doi.org/10.1182/blood.v110.11.2344.2344.

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Abstract Directly radiolabeled anti-CD20 IgGs approved for the treatment of follicular and transformed non-Hodgkin lymphoma produce higher response rates than rituximab. However, these treatments result in severe and protracted hematologic toxicity, which is directly related to the slow blood clearance of these radiolabeled products. Pretargeting procedures separate radionuclide-targeting from the slow antibody-targeting step, and because the radiolabeled compound is small in size, it clears rapidly and thoroughly from the blood and body in just a few hours, minimizing radiation exposure. We have developed a novel recombinant and humanized Tri-Fab bispecific antibody (bsMAb) for pretargeting using the modular Dock-and-Lock procedure. This bsMAb divalently binds to CD20, with the monovalent Fab binding to a unique peptide hapten (HSG) that carries the therapeutic radionuclide. Nude mice bearing established (0.5 to 0.9 cm3) subcutaneous Ramos human B-cell lymphomas were given a single dose of either a 90Y-humanized anti-CD20 IgG (150 and 175 μCi; 50 μg) or a bsMAb-pretargeted 90Y-DOTA-HSG-peptide (150, 250, 500, and 700 μCi). Tissue counting data derived 24 h after injecting the radiolabeled product showed similar tumor uptake between the IgG and pretargeted peptide, but tumor/blood ratios were &gt;1000:1 for the pretargeted peptide vs. 1:1 for the IgG. At both 90Y-IgG doses, blood counts decreased ∼90% for 2 weeks after treatment, while the pretargeted groups only decreased ∼60% at the 700 μCi dose to as low as a 25% decrease at the 250 μCi dose, with full recoveries occurring within 2 weeks of the nadir. The severe hematologic toxicity also resulted in 2/10 and 4/10 deaths within 2 weeks of the 150- and 175-μCi 90Y-IgG doses, respectively. In the remaining animals, after experiencing an initial response, all tumors progressed to ≥1.5 cm3 within 3 weeks of treatment. Only 1/10 animals given 500 μCi of the pretargeted dose showed tumor progression, with all others in this group and the 700-μCi-group showing no evidence of disease. Earlier studies have shown 40%, 59%, and 90% cure rates after 14 to 18 weeks evaluation with 150, 250, and 500 μCi, respectively, of the bsMAb-pretargeted 90Y-peptide (n = 10 to 22 animals). These studies demonstrate that bsMAb pretargeting significantly improves response rates, with durable cures and without the excessive hematologic toxicity commonly associated with directly radiolabeled antibodies. (Supported in part from USPHS grant P01-CA103985.)
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37

Mosayebnia, Mona, Maliheh Hajiramezanali, and Soraya Shahhosseini. "Radiolabeled Peptides for Molecular Imaging of Apoptosis." Current Medicinal Chemistry 27, no. 41 (December 8, 2020): 7064–89. http://dx.doi.org/10.2174/0929867327666200612152655.

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Apoptosis is a regulated cell death induced by extrinsic and intrinsic stimulants. Tracking of apoptosis provides an opportunity for the assessment of cardiovascular and neurodegenerative diseases as well as monitoring of cancer therapy at early stages. There are some key mediators in apoptosis cascade, which could be considered as specific targets for delivering imaging or therapeutic agents. The targeted radioisotope-based imaging agents are able to sensitively detect the physiological signal pathways which make them suitable for apoptosis imaging at a single-cell level. Radiopeptides take advantage of both the high sensitivity of nuclear imaging modalities and favorable features of peptide scaffolds. The aim of this study is to review the characteristics of those radiopeptides targeting apoptosis with different mechanisms.
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38

Saxena, Tanya, Claire Sie, Kristine Lin, Daisy Ye, Katayoun Saatchi, and Urs O. Häfeli. "Potential of Nuclear Imaging Techniques to Study the Oral Delivery of Peptides." Pharmaceutics 14, no. 12 (December 15, 2022): 2809. http://dx.doi.org/10.3390/pharmaceutics14122809.

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Peptides are small biomolecules known to stimulate or inhibit important functions in the human body. The clinical use of peptides by oral delivery, however, is very limited due to their sensitive structure and physiological barriers present in the gastrointestinal tract. These barriers can be overcome with chemical and mechanical approaches protease inhibitors, permeation enhancers, and polymeric encapsulation. Studying the success of these approaches pre-clinically with imaging techniques such as fluorescence imaging (IVIS) and optical microscopy is difficult due to the lack of in-depth penetration. In comparison, nuclear imaging provides a better platform to observe the gastrointestinal transit and quantitative distribution of radiolabeled peptides. This review provides a brief background on the oral delivery of peptides and states examples from the literature on how nuclear imaging can help to observe and analyze the gastrointestinal transit of oral peptides. The review connects the fields of peptide delivery and nuclear medicine in an interdisciplinary way to potentially overcome the challenges faced during the study of oral peptide formulations.
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39

Nag, B., D. Passmore, S. V. Deshpande, and B. R. Clark. "In vitro maximum binding of antigenic peptides to murine MHC class II molecules does not always take place at the acidic pH of the in vivo endosomal compartment." Journal of Immunology 148, no. 2 (January 15, 1992): 369–72. http://dx.doi.org/10.4049/jimmunol.148.2.369.

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Abstract Presentation of Ag to the T cell requires binding of specific peptide fragments of the Ag to MHC II molecules. The ability of a peptide to bind to MHC class II appears to be pH dependent. Recent reports indicate that the binding of peptide to MHC class II molecules takes place primarily within an endosomal compartment of the cell at around pH 5. In this study, we have explored the in vitro pH dependence of peptide binding to different haplotypes of murine MHC class II molecules. The binding of peptides to MHC II was analyzed and quantitated by silica gel TLC, using radiolabeled peptides. The MBP peptide fragments, MBP(1-14)A4 and MBP(88-101)Y88, bound maximally at pH 8 to IAk and IAs, respectively. The binding of PLP peptide fragment, PLP(138-151)Y138, to IAs was maximal at around neutral pH. The maximum binding of an OVA peptide fragment, OVA(323-340)Y340, to IAd, was found to occur at pH 6. Results presented in this report thus suggest that the in vitro maximum binding of peptide is pH dependent and does not always occur at pH 5. The optimum pH range for maximum binding may depend on the nature and net charge of the peptide and its interaction with MHC class II molecules.
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40

Kuhnast, B., C. Bodenstein, R. Haubner, H. J. Wester, R. Senekowitsch-Schmidtke, M. Schwaiger, and W. A. Weber. "Targeting of gelatinase activity with a radiolabeled cyclic HWGF peptide." Nuclear Medicine and Biology 31, no. 3 (April 2004): 337–44. http://dx.doi.org/10.1016/j.nucmedbio.2003.10.011.

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41

Liu, Shuang. "Radiolabeled Cyclic RGD Peptide Bioconjugates as Radiotracers Targeting Multiple Integrins." Bioconjugate Chemistry 26, no. 8 (August 3, 2015): 1413–38. http://dx.doi.org/10.1021/acs.bioconjchem.5b00327.

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42

BUSHNELL, D. "Therapy With Radiolabeled Somatostatin Peptide Analogs for Metastatic Neuroendocrine Tumors." Journal of Gastrointestinal Surgery 10, no. 3 (March 2006): 335–36. http://dx.doi.org/10.1016/j.gassur.2005.08.025.

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43

Pirooznia, Nazanin, Khosrou Abdi, Davood Beiki, Farshad Emami, Seyed Shahriar Arab, Omid Sabzevari, Zahra Pakdin-Parizi, and Parham Geramifar. "Radiosynthesis, Biological Evaluation, and Preclinical Study of a 68Ga-Labeled Cyclic RGD Peptide as an Early Diagnostic Agent for Overexpressed αvβ3 Integrin Receptors in Non-Small-Cell Lung Cancer." Contrast Media & Molecular Imaging 2020 (March 31, 2020): 1–11. http://dx.doi.org/10.1155/2020/8421657.

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The αvβ3 integrin receptors have high expression on proliferating growing tumor cells of different origins including non-small-cell lung cancer. RGD-containing peptides target the extracellular domain of integrin receptors. This specific targeting makes these short sequences a suitable nominee for theranostic application. DOTA-E(cRGDfK)2 was radiolabeled with 68Ga efficiently. The in vivo and in vitro stability was examined in different buffer systems. Metabolic stability was assessed in mice urine. In vitro specific binding, cellular uptake, and internalization were determined. The tumor-targeting potential of [68Ga]Ga-DOTA-E(cRGDfK)2 in a lung cancer mouse model was studied. Besides, the very early diagnostic potential of the 68Ga-labeled RGD peptide was evaluated. The acquisition and reconstruction of the PET-CT image data were also carried out. Radiochemical and radionuclide purity for [68Ga]Ga-DOTA-E(cRGDfK)2 was >%98 and >%99, respectively. Radiotracer showed high in vivo, in vitro, and metabolic stability which was determined by ITLC. The dissociation constant (Kd) of [68Ga]Ga-DOTA-E(cRGDfK)2 was 15.28 nM. On average, more than 95% of the radioactivity was specific binding (internalized + surface-bound) to A549 cells. Biodistribution data showed that radiolabeled peptides were accumulated significantly in A549 tumor and excreted rapidly by the renal system. Tumor uptake peaks were at 1-hour postinjection for [68Ga]Ga-DOTA-E(cRGDfK)2. The tumor was clearly visualized in all images. [68Ga]Ga-DOTA-E(cRGDfK)2 can be used as a peptide-based imaging agent allowing very early detection of different cancers overexpressing αvβ3 integrin receptors and can be a potential candidate in clinical peptide-based imaging for lung cancer.
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44

Fu, Hao, Bulin Du, Zijun Chen, and Yesen Li. "Radiolabeled Peptides for SPECT and PET Imaging in the Detection of Breast Cancer: Preclinical and Clinical Perspectives." Current Medicinal Chemistry 27, no. 41 (December 8, 2020): 6987–7002. http://dx.doi.org/10.2174/0929867327666200128110827.

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Breast cancer is the most common cancer in women worldwide. Due to the heterogeneous nature of breast cancer, the optimal treatment and expected response for each patient may not necessarily be universal. Molecular imaging techniques could play an important role in the early detection and targeted therapy evaluation of breast cancer. This review focuses on the development of peptides labeled with SPECT and PET radionuclides for breast cancer imaging. We summarized the current status of radiolabeled peptides for different receptors in breast cancer. The characteristics of radionuclides and major techniques for peptide labeling are also briefly discussed.
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45

Agrawal, Lokesh, Zainab VanHorn-Ali, Edward A. Berger, and Ghalib Alkhatib. "Specific inhibition of HIV-1 coreceptor activity by synthetic peptides corresponding to the predicted extracellular loops of CCR5." Blood 103, no. 4 (February 15, 2004): 1211–17. http://dx.doi.org/10.1182/blood-2003-08-2669.

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Abstract We used synthetic peptides to the extracellular loops (ECLs) of CCR5 to examine inhibitory effects on HIV infection/fusion with primary leukocytes and cells expressing recombinant CCR5. We show for the first time that peptides derived from the first, second, or third ECL caused dose-dependent inhibition of fusion and infection, although with varying potencies and specificities for envelope glycoproteins (Envs) from different strains. The first and third ECL peptides inhibited Envs from the R5 Ba-L strain and the R5X4 89.6 strain, whereas the second ECL peptide inhibited Ba-L but not 89.6 Env. None of the peptides affected fusion mediated by Env from the X4 LAV strain. Fusion mediated by Envs from several primary HIV-1 isolates was also inhibited by the peptides. These findings suggest that various HIV-1 strains use CCR5 domains in different ways. Experiments involving peptide pretreatment and washing, modulation of the expression levels of Env and CCR5, analysis of CCR5 peptide effects against different coreceptors, and inhibition of radiolabeled glycoprotein (gp) 120 binding to CCR5 suggested that the peptide-blocking activities reflect their interactions with gp120. The CCR5-derived ECL peptides thus provide a useful approach to analyze structure–function relationships involved in HIV-1 Env-coreceptor interactions and may have implications for the design of drugs that inhibit HIV infection.
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Judmann, Benedikt, Björn Wängler, Ralf Schirrmacher, Gert Fricker, and Carmen Wängler. "Towards Radiolabeled EGFR-Specific Peptides: Alternatives to GE11." Pharmaceuticals 16, no. 2 (February 11, 2023): 273. http://dx.doi.org/10.3390/ph16020273.

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The human epidermal growth factor receptor (EGFR) is closely related to several cancer-promoting processes and overexpressed on a variety of tumor types, rendering it an important target structure for the imaging and therapy of several malignancies. To date, approaches to develop peptidic radioligands able to specifically address and visualize EGFR-positive tumors have been of limited success. Most of the attempts were based on the lead GE11, as this peptide was previously described to be a highly potent EGFR-specific agent. However, since it has recently been shown that GE11 exhibits an insufficient affinity to the EGFR in monomeric form to be suitable as a basis for the development of tracers based on it, in the present work we investigated which other peptides might be suitable as lead structures for the development of EGFR-specific peptidic radiotracers. For this purpose, we developed 68Ga-labeled radioligands based on the peptides D4, P1, P2, CPP, QRH, EGBP and Pep11, having been described before as EGFR-specific. In addition, we also tested three truncated versions of the endogenous EGFR ligand hEGF (human epidermal growth factor) with respect to their ability to specifically target the EGFR with high affinity. Therefore, chelator-modified labeling precursors of the mentioned peptides were synthesized, radiolabeled with 68Ga and the obtained radioligands were evaluated for their hydrophilicity/lipophilicity, stability against degradation by human serum peptidases, in vitro tumor cell uptake, and receptor affinity in competitive displacement experiments on EGFR-positive A431 cells. Although all NODA-GA-modified (NODA-GA: (1,4,7-triazacyclononane-4,7-diyl)diacetic acid-1-glutaric acid) labeling precursors could be obtained more or less efficient in yields between 5 and 74%, the 68Ga-radiolabeling proved to be unsuccessful for two of the three truncated versions of hEGF ([68Ga]Ga-8 and [68Ga]Ga-9), producing several side-products. For the other agents [68Ga]Ga-1–[68Ga]Ga-7, [68Ga]Ga-10 and [68Ga]Ga-11, high radiochemical yields and purities of ≥ 98% and molar activities of up to 114 GBq/µmol were obtained. In the assay investigating the radiopeptide susceptibilities against serum peptidase degradation, the EGBP-based agent demonstrated a limited stability with a half-life of only 66.4 ± 3.0 min, whereas the other tracers showed considerably higher stabilities of up to an 8000 min half-life. Finally, all radiotracer candidates were evaluated in terms of tumor cell internalization and receptor binding potential on EGFR-positive A431 cell. In these experiments, all developed agents failed to show an EGFR-specific tumor cell uptake or a relevant EGFR-affinity. By contrast, the positive controls tested under identical conditions, [125I]I-hEGF and hEGF demonstrated the expected high EGFR-specific tumor cell uptake (33.6% after 1 h, being reduced to 1.9% under blocking conditions) and affinity (IC50 value of 15.2 ± 3.3 nM). Thus, these results indicate that none of the previously described peptidic agents developed for EGFR targeting appears to be a reasonable choice as a lead structure for the development of radiopeptides for targeting of EGFR-positive tumors. Likewise, the tested truncated variants of the endogenous hEGF do not seem to be promising alternatives for this purpose.
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47

Liu, Yang, Mei Tian, and Hong Zhang. "Microfluidics for Synthesis of Peptide-Based PET Tracers." BioMed Research International 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/839683.

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Positron emission tomography (PET) is a powerful noninvasive tool for acquisition of the physiological parameters in human and animals with the help of PET tracers. Among all the PET tracers, radiolabeled peptides have been widely explored for cancer-related receptor imaging due to their high affinity and specificity to receptors. But radiochemistry procedures for production of peptide-based PET tracers are usually complex, which makes large-scale clinical studies relatively challenging. New radiolabeling technologies which could simplify synthesis and purification procedures, are extremely needed. Over the last decade, microfluidics and lab-on-a-chip (LOC) technology have boomed as powerful tools in the field of organic chemistry, which potentially provide significant help to the PET chemistry. In this minireview, microfluidic radiolabeling technology is described and its application for synthesis of peptide-based PET tracers is summarized and discussed.
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48

Jiang, Lei, Zheng Miao, Richard H. Kimura, Adam P. Silverman, Gang Ren, Hongguang Liu, Hankui Lu, Jennifer R. Cochran, and Zhen Cheng. "I111n-Labeled Cystine-Knot Peptides Based on the Agouti-Related Protein for Targeting Tumor Angiogenesis." Journal of Biomedicine and Biotechnology 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/368075.

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Agouti-related protein (AgRP) is a 4-kDa cystine-knot peptide of human origin with four disulfide bonds and four solvent-exposed loops. The cell adhesion receptor integrinαvβ3is an important tumor angiogenesis factor that determines the invasiveness and metastatic ability of many malignant tumors. AgRP mutants have been engineered to bind to integrinαvβ3with high affinity and specificity using directed evolution. Here, AgRP mutants 7C and 6E were radiolabeled with111In and evaluated forin vivotargeting of tumor integrinαvβ3receptors. AgRP peptides were conjugated to the metal chelator 1, 4, 7, 10-tetra-azacyclododecane- N,N′,N″,N‴-tetraacetic acid (DOTA) and radiolabeled with111In. The stability of the radiopeptides111In-DOTA-AgRP-7C and111In-DOTA-AgRP-6E was tested in phosphate-buffered saline (PBS) and mouse serum, respectively. Cell uptake assays of the radiolabeled peptides were performed in U87MG cell lines. Biodistribution studies were performed to evaluate thein vivoperformance of the two resulting probes using mice bearing integrin-expressing U87MG xenograft tumors. Both AgRP peptides were easily labeled with111In in high yield and radiochemical purity (>99%). The two probes exhibited high stability in phosphate-buffered saline and mouse serum. Compared with111In-DOTA-AgRP-6E,111In-DOTA-AgRP-7C showed increased U87MG tumor uptake and longer tumor retention (5.74±1.60and1.29±0.02%ID/g at 0.5 and 24 h, resp.), which was consistent with measurements of cell uptake. Moreover, the tumor uptake of111In-DOTA-AgRP-7C was specifically inhibited by coinjection with an excess of the integrin-binding peptidomimetic c(RGDyK). Thus,111In-DOTA-AgRP-7C is a promising probe for targeting integrinαvβ3positive tumors in living subjects.
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49

Rosiere, T. K., J. A. Marrs, and G. B. Bouck. "A 39-kD plasma membrane protein (IP39) is an anchor for the unusual membrane skeleton of Euglena gracilis." Journal of Cell Biology 110, no. 4 (April 1, 1990): 1077–88. http://dx.doi.org/10.1083/jcb.110.4.1077.

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The major integral plasma membrane protein (IP39) of Euglena gracilis was radiolabeled, peptide mapped, and dissected with proteases to identify cytoplasmic domains that bind and anchor proteins of the cell surface. When plasma membranes were radioiodinated and extracted with octyl glucoside, 98% of the extracted label was found in IP39 or the 68- and 110-kD oligomers of IP39. The octyl glucoside extracts were incubated with unlabeled cell surface proteins immobilized on nitrocellulose (overlays). Radiolabel from the membrane extract bound one (80 kD) of the two (80 and 86 kD) major membrane skeletal protein bands. Resolubilization of the bound label yielded a radiolabeled polypeptide identical in Mr to IP39. Intact plasma membranes were also digested with papain before or after radioiodination, thereby producing a cytoplasmically truncated IP39. The octyl glucoside extract of truncated IP39 no longer bound to the 80-kD membrane skeletal protein in the nitrocellulose overlays. EM of intact or trypsin digested plasma membranes incubated with membrane skeletal proteins under stringent conditions similar to those used in the nitrocellulose overlays revealed a partially reformed membrane skeletal layer. Little evidence of a membrane skeletal layer was found, however, when plasma membranes were predigested with papain before reassociation. A candidate 80-kD binding domain of IP39 has been tentatively identified as a peptide fragment that was present after trypsin digestion of plasma membranes, but was absent after papain digestion in two-dimensional peptide maps of IP39. Together, these data suggest that the unique peripheral membrane skeleton of Euglena binds to the plasma membrane through noncovalent interactions between the major 80-kD membrane skeletal protein and a small, papain sensitive cytoplasmic domain of IP39. Other (62, 51, and 25 kD) quantitatively minor peripheral proteins also interact with IP39 on the nitrocellulose overlays, and the possible significance of this binding is discussed.
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50

Widmann, C., J. L. Maryanski, P. Romero, and G. Corradin. "Differential stability of antigenic MHC class I-restricted synthetic peptides." Journal of Immunology 147, no. 11 (December 1, 1991): 3745–51. http://dx.doi.org/10.4049/jimmunol.147.11.3745.

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Abstract Various synthetic peptides recognized as Ag by CTL in the context of MHC class I molecules were tested for stability in vitro and in vivo. Peptide inactivation in vitro was quantitated by titrating the amount of peptide required to sensitize target cells for lysis by specific CTL clones. The degree of inactivation after overnight incubation at 37 degrees C varied widely among a series of antigenic peptides. Some were nearly unaffected, whereas others lost activity by more than 100-fold or even 10,000-fold. However, no correlation was found between susceptibility to serum inactivation and antigenic potency as measured in short term cytolytic assays. No inactivation occurred at 4 degrees C, or at 37 degrees C in the absence of serum, under the conditions used. Serum inactivation most likely involved proteolysis because it could be inhibited by protease inhibitors. Moreover, presumed cleavage products of a radiolabeled susceptible peptide could be visualized by TLC. In vivo, the persistence of the antigenic activity of the injected peptides, either in extracellular fluids or on tumor target cells growing in an ascites form, correlated with the degree of stability found for the peptides in vitro. The differential stability of synthetic peptides may have important consequences for attempts to manipulate the development of an immune response in vivo.
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