Articoli di riviste: "Metal-Chelating peptides"

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Matsubara, Teruhiko, Yuko Hiura e Katsuhiro Kawashiro. "Biocombinatorial Selection of Metal Ion-Chelating Peptides". International Journal of Modern Physics B 17, n. 08n09 (10 aprile 2003): 1324–28. http://dx.doi.org/10.1142/s0217979203018946.

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A phage-displayed library selection was performed to obtain metal ion-chelating peptides. A dodecamer (12-mer) random peptide library was displayed on the surface of filamentous bacterial phage and subjected to an affinity selection. Four rounds of the selection gave fourteen Zn2+-positive phage clones. Enzyme-linked immunosorbent assay showed that the selected clones specifically bound to Zn2+ and Ni2+, but not to Cu2+ and Fe3+. Deduced amino acid sequences of the clones had histidine-rich consensus motifs. These chelating peptides should be applied to designing for metal ion-trapping biomaterials.

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Lu, WeiTao, e ChunMing Dong. "Research progress of metal chelating peptides". Food and Health 4, n. 4 (2022): 19. http://dx.doi.org/10.53388/fh20221101019.

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Kani, Hatice K., Ebru K. Kocazorbaz e Figen Zihnioglu. "Investigation and isolation of peptide based antiglycating agents from various sources". Turkish Journal of Biochemistry 44, n. 5 (25 ottobre 2019): 699–705. http://dx.doi.org/10.1515/tjb-2018-0294.

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Abstract Background In this work, peptide based antiglycation agents from various sources against the advanced glycation endproducts (AGE) formation was investigated. Materials and methods As a source of peptides with deglycating activity, Glycine max, Hordeum vulgare, Triticum aestivum, Avena sativa, Prunus dulcis ve Juglans regia were used. The metal chelating activity and antioxidant activity were determined by Cu(II) chelating activity and CUPRAC (Cupric Reducing Antioxidant Capacity) methods. Antidiabetic activity was evaluated through BSA-glucose model. Results Most of the extracts obtained have inhibitory activity against AGE formation. Among all plant peptide isolates soybean was found to be most efficient by means of antiglycating (IC50 1.33 μg/mL), antioxidant (28.2 ± 1.4 μmol AAE/mg) and metal chelation activity (55%). Conclusion As a result, this study can provide preliminary data to literature to support researches those focused on peptide based glycation inhibitors and discovery of potent AGE inhibitory peptides.

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Chan, Pei-Teng, Patricia Matanjun, Cahyo Budiman, Rossita Shapawi e Jau-Shya Lee. "Novel Peptide Sequences with ACE-Inhibitory and Antioxidant Activities Derived from the Heads and Bones of Hybrid Groupers (Epinephelus lanceolatus × Epinephelus fuscoguttatus)". Foods 11, n. 24 (9 dicembre 2022): 3991. http://dx.doi.org/10.3390/foods11243991.

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The heads and bones of hybrid groupers are potential precursors for angiotensin-converting enzyme (ACE)-inhibitory and antioxidant peptides. The aim of this study was to isolate the dual-action peptides from the Alcalase-treated head and bone hydrolysate of hybrid groupers followed by identification of the novel peptides. The stability of these peptides against stimulated in vitro gastrointestinal digestion (SGID) was also determined. Fraction HB-IV (less than 1 kDa) obtained from ultrafiltration showed the strongest ACE-inhibition ability (IC50: 0.28 mg/mL), which was comparable to the potency of the commercial supplement, PeptACE (IC50: 0.22 mg/mL). This fraction also demonstrated the highest hydroxyl radical scavenging and metal-chelating activities. However, further fractionation of HB-IV by a series of chromatography resulted in peptide fractions of reduced ACE-inhibitory and antioxidant activities. The hydroxyl radical scavenging and reduction potential of HB-IV were enhanced, whereas ACE-inhibitory and metal-chelating activities were reduced following SGID. A total of 145 peptide sequences were identified from HB-IV, of which 137 peptides were novel to the BIOPEP database. The results suggested that the bioactive peptides isolated from the heads and bones of hybrid groupers could be used as functional foods/ingredients with potential ACE-inhibitory and antioxidant effects.

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Daubit, Isabelle Marie, e Nils Metzler-Nolte. "On the interaction of N-heterocyclic carbene Ir+I complexes with His and Cys containing peptides". Dalton Transactions 48, n. 36 (2019): 13662–73. http://dx.doi.org/10.1039/c9dt01338e.

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In the interaction of an [Ir(+i)(COD)(NHC)Cl] complex with model peptides a chelating motif with a particularly interesting bimetallic peptide-bridged Ir(+iii)–NHC motif was identified with loss of the COD and Cl ligands and oxidation of the metal.

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Irankunda, Rachel, Jairo Andrés Camaño Echavarría, Cédric Paris, Loïc Stefan, Stéphane Desobry, Katalin Selmeczi, Laurence Muhr e Laetitia Canabady-Rochelle. "Metal-Chelating Peptides Separation Using Immobilized Metal Ion Affinity Chromatography: Experimental Methodology and Simulation". Separations 9, n. 11 (14 novembre 2022): 370. http://dx.doi.org/10.3390/separations9110370.

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Metal-Chelating Peptides (MCPs), obtained from protein hydrolysates, present various applications in the field of nutrition, pharmacy, cosmetic etc. The separation of MCPs from hydrolysates mixture is challenging, yet, techniques based on peptide-metal ion interactions such as Immobilized Metal Ion Affinity Chromatography (IMAC) seem to be efficient. However, separation processes are time consuming and expensive, therefore separation prediction using chromatography modelling and simulation should be necessary. Meanwhile, the obtention of sorption isotherm for chromatography modelling is a crucial step. Thus, Surface Plasmon Resonance (SPR), a biosensor method efficient to screen MCPs in hydrolysates and with similarities to IMAC might be a good option to acquire sorption isotherm. This review highlights IMAC experimental methodology to separate MCPs and how, IMAC chromatography can be modelled using transport dispersive model and input data obtained from SPR for peptides separation simulation.

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Luisi, Grazia, Azzurra Stefanucci, Gokhan Zengin, Marilisa Dimmito e Adriano Mollica. "Anti-Oxidant and Tyrosinase Inhibitory In Vitro Activity of Amino Acids and Small Peptides: New Hints for the Multifaceted Treatment of Neurologic and Metabolic Disfunctions". Antioxidants 8, n. 1 (26 dicembre 2018): 7. http://dx.doi.org/10.3390/antiox8010007.

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Oxidative damage is among the factors associated with the onset of chronic pathologies, such as neurodegenerative and metabolic diseases. Several classes of anti-oxidant compounds have been suggested as having a protective role against cellular stressors, but, in this perspective, peptides’ world represents a poorly explored source. In the present study, the free radical scavenging properties, the metal ion reducing power, and the metal chelating activity of a series of sulfurated amino acids and tripeptides were determined in vitro through canonical assays (DPPH, ABTS, CUPRAC, FRAP, PM, and EECC) and estimated in comparison with the corresponding activities of synthetic peptide semicarbazones, incorporating the peculiar non-proteinogenic amino acid, tert-leucine (tLeu). The compounds exhibited remarkable anti-oxidant properties. As expected, sulfurated compounds 1–5 were found to be the most efficient radical scavengers and strongest reductants. Nevertheless, tLeu-containing peptides 7 and 8 disclosed notable metal reducing and chelating activities. These unprecedented results indicate that tLeu-featuring di- and tripeptide backbones, bearing the semicarbazone chelating moiety, are compatible with the emergence of an anti-oxidant potential. Additionally, when tested against a panel of enzymes usually targeted for therapeutic purposes in neurodegenerative and metabolic disorders, all samples were found to be good inhibitors of tyrosinase.

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Fisher, A. E. O., e D. P. Naughton. "Metal ion chelating peptides with superoxide dismutase activity". Biomedicine & Pharmacotherapy 59, n. 4 (maggio 2005): 158–62. http://dx.doi.org/10.1016/j.biopha.2005.03.008.

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Gallegos Tintoré, Santiago, Cristina Torres Fuentes, Javier Solorza Feria, Manuel Alaiz, Julio Girón Calle, Alma Leticia Martínez Ayala, Luis Chel Guerrero e Javier Vioque. "Antioxidant and Chelating Activity of NontoxicJatropha curcasL. Protein Hydrolysates Produced byIn VitroDigestion Using Pepsin and Pancreatin". Journal of Chemistry 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/190129.

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The antioxidant and metal chelating activities inJ. curcasprotein hydrolysates have been determined. The hydrolysates were produced by treatment of a nontoxic genotype with the digestive enzymes pepsin and pancreatin and then were characterized by fast protein liquid chromatography and reverse phase chromatography. Peptidic fractions with higher radical scavenging activity were analysed by matrix-assisted laser desorption/ionization mass spectrometry. The antioxidant activity was determined by measuring inhibition of the oxidative degradation ofβ-carotene and by measuring the reactive oxygen species (ROS) in Caco-2 cell cultures. Cu2+and Fe2+chelating activities were also determined. The hydrolysates inhibited the degradation ofβ-carotene and the formation of ROS in Caco-2 cells. The lower molecular weight peptidic fractions from FPLC had stronger antioxidant activity in cell cultures compared with the hydrolysates, which correlated with a higher content in antioxidant and chelating amino acids. These fractions were characterized by a large presence of peptides with different molecular masses. The hydrolysates exhibited both Cu2+and Fe2+chelating activity. It was concluded thatJ. curcasis a good source of antioxidant and metal chelating peptides, which may have a positive impact on the economic value of this crop, as a potential source of food functional components.

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Irankunda, Rachel, Jairo Andrés Camaño Echavarría, Cédric Paris, Katalin Selmeczi, Loïc Stefan, Sandrine Boschi-Muller, Laurence Muhr e Laetitia Canabady-Rochelle. "Deciphering Interactions Involved in Immobilized Metal Ion Affinity Chromatography and Surface Plasmon Resonance for Validating the Analogy between Both Technologies". Inorganics 12, n. 1 (16 gennaio 2024): 31. http://dx.doi.org/10.3390/inorganics12010031.

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Various peptides can be obtained through protein enzymatic hydrolysis. Immobilized metal ion affinity chromatography (IMAC) is one of the methods which can be used to separate metal chelating peptides (MCPs) in a hydrolysate mixture. In this context, this work aims to understand deeply the interactions in IMAC and surface plasmon resonance (SPR) in order to validate experimentally the analogy between both technologies and to be further able to perform IMAC modeling in the next work using peptide sorption isotherm parameters obtained from SPR. Indeed, chromatography modeling can be used to predict separation of MCPs in IMAC and the knowledge of peptide sorption isotherm obtained from SPR is a crucial step. For this purpose, 22 peptides were selected and investigated in IMAC using HisTrap X-Ni2+ and HiFliQ NTA-Ni2+ columns and were also studied in SPR as well. Results showed that peptides with histidine residues had good affinity to Ni2+, while the high positive charge of peptides was responsible of ionic interactions. Further, most of the peptides with good retention time in IMAC showed a good affinity in SPR as well, which validated experimentally the SPR-IMAC analogy.

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Irankunda, Rachel, Pauline Jambon, Alexandra Marc, Jairo Andrés Camaño Echavarría, Laurence Muhr e Laetitia Canabady-Rochelle. "Simulation of Ni2+ Chelating Peptides Separation in IMAC: Prediction of Langmuir Isotherm Parameters from SPR Affinity Data". Processes 12, n. 3 (15 marzo 2024): 592. http://dx.doi.org/10.3390/pr12030592.

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Chromatography modeling for simulation is a tool that can help to predict the separation of molecules inside the column. Knowledge of sorption isotherms in chromatography modeling is a crucial step and methods such as frontal analysis or batch are used to obtain sorption isotherm parameters, but they require a significant quantity of samples. This study aims to predict Langmuir isotherm parameters from Surface Plasmon Resonance (SPR) affinity data (requiring less quantity of sample) to simulate metal chelating peptides (MCPs) separation in Immobilized Metal ion Affinity Chromatography (IMAC), thanks to the analogy between both techniques. The validity of simulation was evaluated by comparing the peptide’s simulated retention time with its experimental retention time obtained by IMAC. Results showed that the peptide affinity constant (KA) can be conserved between SPR and IMAC. However, the maximal capacity (qmax) must be adjusted by a correction factor to overcome the geometry differences between IMAC (spherical particles) and SPR (plane sensor ship). Therefore, three approaches were studied; the best one was to use qmax,IMAC imidazole determined experimentally while a correction factor was applied on qmax,SPR to obtain the qmax,IMAC of the peptide, thus minimizing the discrepancy between the experimental and simulated retention times of a peptide.

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Wickramasinghe, Hiruni Sashikala, Edirisinghe Dewage Nalaka Sandun Abeyrathne, Ki-Chang Nam e Dong Uk Ahn. "Antioxidant and Metal-Chelating Activities of Bioactive Peptides from Ovotransferrin Produced by Enzyme Combinations". Poultry 1, n. 4 (27 settembre 2022): 220–28. http://dx.doi.org/10.3390/poultry1040019.

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Peptides produced from food sources possess numerous bioactivities that make them useful in improving human health and preventing diseases. Although many studies related to egg protein hydrolysis are available, little work has been conducted on the production of bioactive peptides from apo-ovotransferrin (OTF) using two-step enzyme hydrolysis. The objectives of this study were to produce bioactive peptides from OTF using two enzymes and to determine their functional properties. Lipolyzed OTF was prepared at a concentration of 20 mg/mL and treated with protease (3 h at 55 °C), papain (3 h at 37 °C), elastase (24 h at 25 °C), and α-chymotrypsin (3 h at 37 °C) as the first enzyme treatment. The hydrolysates from the first step of hydrolysis were treated with the above enzymes in different combinations and incubated for 24 h at their optimum temperatures, followed by heat inactivation at the end of each treatment. Based on 15% SDS-PAGE results, the nine best enzyme combinations were selected for further analysis. Papain + protease (PapPro, 0.0075 ± 0.004 malondialdehyde (MDA) mg/kg), α-chymotrypsin + papain (ChyPap, 0.081 ± 0.003 MDA mg/kg), and elastase + α-chymotrypsin (ElaChy, 0.083 ± 0.015 MDA mg/kg) showed strong antioxidant activity. PapPro showed the highest Fe-chelating activity (5.40 ± 0.85%) but lacked Cu-chelating activity. In conclusion, PapPro, ChyPap, and ElaChy treatments of OTF produced peptides with strong antioxidant and Fe-chelating activities but lacked Cu-chelating activity. Thus, ovotransferrin hydrolysates produced using PapPro, ChyPap, and ElaChy treatments have the potential to reduce oxidative stress in the body.

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Dayob, Kenana, Aygul Zengin, Ruslan Garifullin, Mustafa O. Guler, Timur I. Abdullin, Abdulla Yergeshov, Diana V. Salakhieva, Hong Hanh Cong e Mohamed Zoughaib. "Metal-Chelating Self-Assembling Peptide Nanofiber Scaffolds for Modulation of Neuronal Cell Behavior". Micromachines 14, n. 4 (19 aprile 2023): 883. http://dx.doi.org/10.3390/mi14040883.

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Synthetic peptides are promising structural and functional components of bioactive and tissue-engineering scaffolds. Here, we demonstrate the design of self-assembling nanofiber scaffolds based on peptide amphiphile (PA) molecules containing multi-functional histidine residues with trace metal (TM) coordination ability. The self-assembly of PAs and characteristics of PA nanofiber scaffolds along with their interaction with Zn, Cu, and Mn essential microelements were studied. The effects of TM-activated PA scaffolds on mammalian cell behavior, reactive oxygen species (ROS), and glutathione levels were shown. The study reveals the ability of these scaffolds to modulate adhesion, proliferation, and morphological differentiation of neuronal PC-12 cells, suggesting a particular role of Mn(II) in cell-matrix interaction and neuritogenesis. The results provide a proof-of-concept for the development of histidine-functionalized peptide nanofiber scaffolds activated with ROS- and cell-modulating TMs to induce regenerative responses.

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Shu, Guowei, Bowen Zhang, Qian Zhang, Hongchang Wan e Hong Li. "Effect of Temperature, pH, Enzyme to Substrate Ratio, Substrate Concentration and Time on the Antioxidative Activity of Hydrolysates from Goat Milk Casein by Alcalase". Acta Universitatis Cibiniensis. Series E: Food Technology 20, n. 2 (1 dicembre 2016): 29–38. http://dx.doi.org/10.1515/aucft-2016-0013.

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Abstract The effect of hydrolysis temperature (45, 50, 55, 60 and 65°C), pH (7.0, 7.5, 8.0, 8.5 and 9.0), enzyme to substrate (E/S) ratio (1.0, 1.5, 2.0, 2.5 and 3.0%), substrate concentration (2, 3, 4, 5 and 6%) and hydrolysis time (30-240min) on antioxidant peptides hydrolysated from goat’s milk casein by Alcalase was investigated using single factor experiment. In order to obtain high DPPH radical-scavenging activity, metal-chelating activity and superoxide radical scavenging activity, the optimal conditions were hydrolysis time of 150 min, temperature of 50°C, pH 8.0, E/S ratio of 2.0% and substrate concentration of 4.0%. The hydrolysis time, hydrolysis temperature, pH, E/S ratio and substrate concentration had a significant influence on degree of hydrolysis, metal-chelating activity, DPPH and superoxide radical scavenging activity on casein hydrolysate of goat milk by Alcalase, the results were beneficial for further provide theoretical basis for production of antioxidant peptides.

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Cheng, Ching-Wen, Kuo-Chin Lin, Fu-Ming Pan, Supachok Sinchaikul, Chi-Huey Wong, Wei-Chih Su, Ching-Hsiang Hsu e Shui-Tein Chen. "Facile synthesis of metal-chelating peptides on chip for protein array". Bioorganic & Medicinal Chemistry Letters 14, n. 8 (aprile 2004): 1987–90. http://dx.doi.org/10.1016/j.bmcl.2004.01.084.

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Magrì, Antonio, Diego La Mendola e Enrico Rizzarelli. "Nerve Growth Factor Peptides Bind Copper(II) with High Affinity: A Thermodynamic Approach to Unveil Overlooked Neurotrophin Roles". International Journal of Molecular Sciences 22, n. 10 (11 maggio 2021): 5085. http://dx.doi.org/10.3390/ijms22105085.

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Nerve growth factor (NGF) is a protein essential to neurons survival, which interacts with its receptor as a non-covalent dimer. Peptides belonging to NGF N-terminal domain are able to mimic the activity of the whole protein. Such activity is affected by the presence of copper ions. The metal is released in the synaptic cleft where proteins, not yet identified, may bind and transfer to human copper transporter 1 (hCtr1), for copper uptake in neurons. The measurements of the stability constants of copper complexes formed by amyloid beta and hCtr1 peptide fragments suggest that beta-amyloid (Aβ) can perform this task. In this work, the stability constant values of copper complex species formed with the dimeric form of N-terminal domain, sequence 1–15 of the protein, were determined by means of potentiometric measurements. At physiological pH, NGF peptides bind one equivalent of copper ion with higher affinity of Aβ and lower than hCtr1 peptide fragments. Therefore, in the synaptic cleft, NGF may act as a potential copper chelating molecule, ionophore or chaperone for hCtr1 for metal uptake. Copper dyshomeostasis and mild acidic environment may modify the balance between metal, NGF, and Aβ, with consequences on the metal cellular uptake and therefore be among causes of the Alzheimer’s disease onset.

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Shoshan, Michal S. "Will Short Peptides Revolutionize Chelation Therapy?" CHIMIA 76, n. 9 (21 settembre 2022): 744. http://dx.doi.org/10.2533/chimia.2022.744.

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It will soon be twenty years since the last chelating agent was clinically approved to be used against toxic metals. Even though metal poisoning has been known to humankind for centuries, only about a dozen compounds, all of which are small molecules, compose the pharmaceutical toolbox to expel intrinsically toxic or essential but misregulated metals. These compounds widely suffer from various drawbacks, most critically, poor metal selectivity. Can medicinal inorganic chemistry offer modern solutions to these old challenges? In this perspective, the opportunities and advantages of harnessing short peptides for chelation therapy are described. While broadly aiming to address various toxic metals, achievements in targeting lead (Pb) with peptides reveal the unexplored potential hidden in this chemical space and raise the possibility that peptides may reform chelation therapy.

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Lupaescu, Ancuta-Veronica, Ion Sandu, Brindusa Alina Petre, Laura Ion, Catalina-Ionica Ciobanu e Gabi Drochioiu. "NAP Neuroprotective Peptide and its Analogs: Simultaneously Copper and Iron Binding and Reduction". Revista de Chimie 70, n. 5 (15 giugno 2019): 1784–90. http://dx.doi.org/10.37358/rc.19.5.7215.

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Neurodegenerative diseases, including Alzheimer disease, involve mechanisms such as protein aggregation, free radical generation and oxidative stress. Transition metals such as copper and iron were linked to neurodegenerative pathology. Their pathogenic role consists in generating different reactive oxygen species and damaging tissues or cells through the Fenton reaction. Abnormal metabolism of copper and iron can lead to several chronic pathogenesis. NAP is a small active fragment of activity-dependent neuroprotective protein essential for brain formation. NAP peptide showed neuroprotective proprieties against toxicity induced by the �-amyloid peptide, N-methyl-D-aspartate, electrical blockade, the envelope protein of the AIDS virus, dopamine, H2O2, and nutrient starvation in cell culture. Therefore, we investigated here the interaction of Cu2+ and Fe3+ ions with the NAP neuroprotective peptide and its analogs. With MALDI-ToF mass spectrometry, the formation of reduced metal-peptide complexes and the metal chelating properties of NAP-like neuroprotective peptides were highlighted.

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Liu, Wang, Yin, Liu, Qin, Nakamura, Shahidi, Yu, Zhou e Zhu. "Zinc-Chelating Mechanism of Sea Cucumber (Stichopus japonicus)-Derived Synthetic Peptides". Marine Drugs 17, n. 8 (25 luglio 2019): 438. http://dx.doi.org/10.3390/md17080438.

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In this study, three synthetic zinc-chelating peptides (ZCPs) derived from sea cucumber hydrolysates with limited or none of the common metal-chelating amino-acid residues were analyzed by flame atomic absorption spectroscopy, circular dichroism spectroscopy, size exclusion chromatography, zeta-potential, Fourier transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy. The amount of zinc bound to the ZCPs reached maximum values with ZCP:zinc at 1:1, and it was not further increased by additional zinc presence. The secondary structures of ZCPs were slightly altered, whereas no formation of multimers was observed. Furthermore, zinc increased the zeta-potential value by neutralizing the negatively charged residues. Only free carboxyl in C-terminus of ZCPs was identified as the primary binding site of zinc. These results provide the theoretical foundation to understand the mechanism of zinc chelation by peptides.

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Sauser, Luca, e Michal S. Shoshan. "Enhancing Metal-binding with Noncanonical Coordinating Amino Acids". CHIMIA International Journal for Chemistry 75, n. 6 (30 giugno 2021): 530–34. http://dx.doi.org/10.2533/chimia.2021.530.

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More than 50% of proteinogenic amino acid sidechains can bind metal ions, enabling proteins and peptides to bear these ions as cofactors. Nevertheless, post-translational modifications and incorporation of noncanonical amino acids bestow peptides and proteins myriads of other coordination capabilities, thanks to an enhanced metal binding. Here we summarize selected examples of natural and artificial systems that contain one or more noncanonical amino acids coordinating a metal ion and subsequently achieve a new or enhanced function. We report on a wide array of systems: from disease-related proteins that undergo sulfurylation or phosphorylation through natural metallophores that selectively capture precious essential ions to synthetic selfassembly strategies, biocatalysts, and chelating agents against toxic metals. Regardless of their (bio)synthetic routes, all possess unique metal-binding properties that could not be effectively achieved by systems composed of canonical residues.

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Chunkao, Siriporn, Wirote Youravong, Chutha T. Yupanqui, Adeola M. Alashi e Rotimi E. Aluko. "Structure and Function of Mung Bean Protein-Derived Iron-Binding Antioxidant Peptides". Foods 9, n. 10 (3 ottobre 2020): 1406. http://dx.doi.org/10.3390/foods9101406.

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An iron-binding mung bean protein hydrolysate (MBPH) was prepared using a continuous enzymatic membrane reactor followed by peptide separation on anion-exchange (AEC) and reverse-phase HPLC (RP-HPLC) columns. Amino acid sequences of peptides present in the RP-HPLC fraction with the strongest iron-binding capacity were identified using mass spectrometry, and ten peptides of 5–8 amino acids synthesized for antioxidant characterization. Five fractions (AF1– AF5) with higher iron-binding capacity (88.86 ± 6.43 to 153.59 ± 2.18 mg/g peptide) when compared to the MBPH (36.81 ± 0.93 mg/g peptide) were obtained from AEC. PAIDL had the significantly (p < 0.05) highest iron-binding capacity, but LLLLG and LLGIL showed the strongest metal chelating activity. However, PAIDL (46.63%) and LLGIL (81.27%) had significantly (p < 0.05) better DPPH radical scavenging activity than the other peptides. PAIDL and LLGIL were also the most effective (p < 0.05) hydroxyl radical neutralizers with an effective concentration that scavenged 50% (EC50) values of 0.09 and 0.37 mM, respectively. PAIDL and AIVIL showed the lowest EC50 values of 0.07 mM each for superoxide radical scavenging activity. We conclude that short chain length in combination with leucine as the C-terminal amino acid residue contributed to the strong antioxidant properties of peptides in this study.

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Bjørlie, Mads, Julie Christina Hartmann, Line Hyrup Rasmussen, Betül Yesiltas, Ann-Dorit Moltke Sørensen, Simon Gregersen Echers e Charlotte Jacobsen. "Screening for Metal-Chelating Activity in Potato Protein Hydrolysates Using Surface Plasmon Resonance and Peptidomics". Antioxidants 13, n. 3 (13 marzo 2024): 346. http://dx.doi.org/10.3390/antiox13030346.

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Metal-catalyzed lipid oxidation is a major factor in food waste, as it reduces shelf life. Addressing this issue, our study investigates the potential of hydrolysates derived from potato protein, a by-product of potato starch production, as metal-chelating antioxidants. Through sequential enzymatic hydrolysis using alcalase or trypsin combined with Flavourzyme, we produced various hydrolysates, which were then fractionated using ultrafiltration. Using a combination of peptidomics and bioinformatics, we predicted the presence of metal-chelating and free radical-scavenging peptides across all hydrolysate fractions, with a trend indicating a higher content of antioxidant peptides in lower molecular weight fractions. To validate these predictions, we utilized surface plasmon resonance (SPR) and a 9-day emulsion storage experiment. While SPR demonstrated potential in identifying antioxidant activity, it faced challenges in differentiating between hydrolysate fractions due to significant standard errors. In the storage experiment, all hydrolysates showed lipid oxidation inhibition, though not as effectively as ethylenediaminetetraacetic acid (EDTA). Remarkably, one fraction (AF13) was not significantly different (p < 0.05) from EDTA in suppressing hexanal formation. These results highlight SPR and peptidomics/bioinformatics as promising yet limited methods for antioxidant screening. Importantly, this study reveals the potential of potato protein hydrolysates as antioxidants in food products, warranting further research.

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Nowak, J., e H. Tsai. "The yeast aminopeptidase Y". Canadian Journal of Microbiology 34, n. 2 (1 febbraio 1988): 118–24. http://dx.doi.org/10.1139/m88-024.

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A metal-dependent aminopeptidase (EC 3.4.11.-), designated APase Y, has been purified to homogeneity by conventional methods. The enzyme is composed of a single polypeptide chain with molecular mass of 102 kilodaltons, estimated by sodium dodecyl sulphate – polyacrylamide gel electrophoresis, with a blocked N-terminal amino acid. It possesses neither endopeptidase nor carboxypeptidase activity and is strongly inhibited by metal-chelating agents, Zn2+, and the protein inhibitor from Neurospora crassa. APase Y is insensitive to Cl anions, S—S reducing reagents, serine protease inhibitors, and the peptidase inhibitor benzamidine. Co2+, Hg2+, and p-chloromercuribenzoate can activate the enzyme up to 22, 20, and 55%, respectively. The holoenzyme is resistant to yeast endopeptidases A, B, and Y, whereas the apoenzyme (obtained after treatment with chelators) is susceptible to the serine endopeptidases B and Y. The enzyme catalyzes hydrolysis of most L peptides possessing free α-amino (or imino) group by stepwise removal of N-terminal residue. Peptides with L-leucine at the N terminus are cleaved preferentially. The enzyme is unable to catalyze hydrolysis of X—Pro type peptide bonds, and inefficiently hydrolyzes bonds between Asp—X and Glu—X. L-leucine p-nitroanilide hydrolyzes optimally at pH 8.2 with a Km value of 1 mM. The purified enzyme is stable during storage in 0.05 M phosphate buffer, pH 6.7, containing 40–50% glycerol, at −20 °C.

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Yu, Xuening, Xiaoyang Liu e Dayong Zhou. "A critical review of a typical research system for food‐derived metal‐chelating peptides: Production, characterization, identification, digestion, and absorption". Comprehensive Reviews in Food Science and Food Safety 23, n. 1 (13 dicembre 2023): 1–30. http://dx.doi.org/10.1111/1541-4337.13277.

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AbstractIn the past decade, food‐derived metal‐chelating peptides (MCPs) have attracted significant attention from researchers working towards the prevention of metal (viz., iron, zinc, and calcium) deficiency phenomenon by primarily inhibiting the precipitation of metals caused by the gastrointestinal environment and exogenous substances (including phytic and oxalic acids). However, for the improvement of limits of current knowledge foundations and future investigation directions of MCP or their derivatives, several review categories should be improved and emphasized. The species’ uniqueness and differences in MCP productions highly contribute to the different values of chelating ability with particular metal ions, whereas comprehensive reviews of chelation characterization determined by various kinds of technique support different horizons for explaining the chelation and offer options for the selection of characterization methods. The reviews of chelation mechanism clearly demonstrate the involvement of potential groups and atoms in chelating metal ions. The discussions of digestive stability and absorption in various kinds of absorption model in vitro and in vivo as well as the theory of involved cellular absorption channels and pathways are systematically reviewed and highlighted compared with previous reports as well. Meanwhile, the chelation mechanism on the molecular docking level, the binding mechanism in amino acid identification level, the utilizations of everted rat gut sac model for absorption, and the involvement of cellular absorption channels and pathway are strongly recommended as novelty in this review. This review makes a novel contribution to the literature by the comprehensive prospects for the research and development of food‐derived mineral supplements.

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Seregin, Ilya V., e Anna D. Kozhevnikova. "Phytochelatins: Sulfur-Containing Metal(loid)-Chelating Ligands in Plants". International Journal of Molecular Sciences 24, n. 3 (26 gennaio 2023): 2430. http://dx.doi.org/10.3390/ijms24032430.

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Phytochelatins (PCs) are small cysteine-rich peptides capable of binding metal(loid)s via SH-groups. Although the biosynthesis of PCs can be induced in vivo by various metal(loid)s, PCs are mainly involved in the detoxification of cadmium and arsenic (III), as well as mercury, zinc, lead, and copper ions, which have high affinities for S-containing ligands. The present review provides a comprehensive account of the recent data on PC biosynthesis, structure, and role in metal(loid) transport and sequestration in the vacuoles of plant cells. A comparative analysis of PC accumulation in hyperaccumulator plants, which accumulate metal(loid)s in their shoots, and in the excluders, which accumulate metal(loid)s in their roots, investigates the question of whether the endogenous PC concentration determines a plant’s tolerance to metal(loid)s. Summarizing the available data, it can be concluded that PCs are not involved in metal(loid) hyperaccumulation machinery, though they play a key role in metal(loid) homeostasis. Unraveling the physiological role of metal(loid)-binding ligands is a fundamental problem of modern molecular biology, plant physiology, ionomics, and toxicology, and is important for the development of technologies used in phytoremediation, biofortification, and phytomining.

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El Hajj, Sarah, Cindy Tatiana Sepúlveda Rincón, Jean-Michel Girardet, Céline Cakir-Kiefer, Loic Stefan, José Edgar Zapata Montoya, Sandrine Boschi-Muller, Caroline Gaucher e Laetitia Canabady-Rochelle. "Electrically Switchable Nanolever Technology for the Screening of Metal-Chelating Peptides in Hydrolysates". Journal of Agricultural and Food Chemistry 69, n. 31 (29 luglio 2021): 8819–27. http://dx.doi.org/10.1021/acs.jafc.1c02199.

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Canabady-Rochelle, Laetitia L. S., Katalin Selmeczi, Sabrina Collin, Andreea Pasc, Laurence Muhr e Sandrine Boschi-Muller. "SPR screening of metal chelating peptides in a hydrolysate for their antioxidant properties". Food Chemistry 239 (gennaio 2018): 478–85. http://dx.doi.org/10.1016/j.foodchem.2017.06.116.

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Canabady-Rochelle, Laetitia L. S., Christelle Harscoat-Schiavo, Violette Kessler, Arnaud Aymes, Frantz Fournier e Jean-Michel Girardet. "Determination of reducing power and metal chelating ability of antioxidant peptides: Revisited methods". Food Chemistry 183 (settembre 2015): 129–35. http://dx.doi.org/10.1016/j.foodchem.2015.02.147.

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Muhr, Laurence, Steve Pontvianne, Katalin Selmeczi, Cédric Paris, Sandrine Boschi‐Muller e Laetitia Canabady‐Rochelle. "Chromatographic separation simulation of metal‐chelating peptides from surface plasmon resonance binding parameters". Journal of Separation Science 43, n. 11 (2 aprile 2020): 2031–41. http://dx.doi.org/10.1002/jssc.201900882.

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Sonklin, Chanikan, Natta Laohakunjit e Orapin Kerdchoechuen. "Assessment of antioxidant properties of membrane ultrafiltration peptides from mungbean meal protein hydrolysates". PeerJ 6 (27 luglio 2018): e5337. http://dx.doi.org/10.7717/peerj.5337.

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Background Bioactive peptides can prevent damage associated with oxidative stress in humans when consumed regularly. Recently, peptides have attracted immense interest because of their beneficial functional properties, safety and little or no side effects when used at high concentration. Most antioxidant peptides are small in size, less than 1 kDa, and contains a high proportion of hydrophobic amino acid. Particularly, tyrosine, leucine, alanine, isoleucine, valine, lysine, phenyalanine, cysteine, methionine and histidine in peptide chain exhibited high antioxidant activity. Mungbean meal protein (MMP) is highly abundant in hydrophobic amino acids. It indicated that MMP might be a good source of antioxidants. Therefore, the objectives were to optimize the conditions used to generate mungbean meal protein hydrolysate (MMPH) with antioxidant activity from bromelain and to investigate the antioxidant activities of different molecular weight (MW) peptide fraction. Methods Response Surface Methodology (RSM) was used for screening of the optimal conditions to produce MMPH. After that MMPH was fractionated using ultrafiltration membranes with different MW distributions. Crude-MMPH and four fractions were investigated for five antioxidant activities: 2,2,1-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, superoxide, ferric reducing antioxidant power (FRAP) and metal ion chelation activity. Results The optimal condition to produce the MMPH was 15% (w/w) of bromelain and hydrolysis time for 12 h which showed the greatest DPPH and ABTS radical scavenging activity. After mungbean protein from optimal condition was separated based on different molecular weight, the DPPH radical scavenging activity was the highest for the F4 (less than 1 kDa) peptide fraction. Metal ion chelating activity was generally weak, except for the F4 that had a value of 43.94% at a protein concentration of 5 mg/mL. The F4 also exhibited high hydroxyl and superoxide activities (54 and 65.1%), but moderate activity for ferric reducing antioxidant power (0.102 mmole Fe2+/g protein) compared to other peptide fractions and crude-MMPH. Molecular weight and amino acid were the main factors that determined the antioxidant activities of these peptide fractions. Results indicated that F4 had strong antioxidant potentials. Discussion The lowest MW fraction (less than 1 kDa) contributed to the highest DPPH, superoxide, hydroxyl and metal chelation activity because influence of low MW and high content of hydrophobic amino acid in peptide chain. Results from this study indicated that MMPH peptides donate protons to free radicals because they had significantly high DPPH value compared to superoxide, hydroxyl and FRAP, which reactions were electron donation. Moreover, MMPH peptides had the ability to inhibit transition metal ions because of highly abundant glutamic acid and aspartic acid in peptide chain.

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Kaugarenia, Nastassia, Sophie Beaubier, Erwann Durand, Arnaud Aymes, Pierre Villeneuve, François Lesage e Romain Kapel. "Optimization of Selective Hydrolysis of Cruciferins for Production of Potent Mineral Chelating Peptides and Napins Purification to Valorize Total Rapeseed Meal Proteins". Foods 11, n. 17 (29 agosto 2022): 2618. http://dx.doi.org/10.3390/foods11172618.

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Preventing oxidation and microbial spoilage are both major concerns in food industries. In this context, this study aimed to valorize the total rapeseed meal proteins with controlled enzymatic proteolysis to generate potent mineral-chelating peptides from cruciferins while keeping intact the antimicrobial napins. Implementation of proteolysis of total rapeseed protein isolate with the Prolyve® enzyme highlighted an interesting selective hydrolysis of the cruciferins. Hence, the mechanism of this particular hydrolysis was investigated through a Design of Experiments method to obtain a model for the prediction of kinetics (cruciferin degradation and napin purity) according to the operating conditions applied. Then, multicriteria optimization was implemented to maximize the napin purity and yield while minimizing both enzymatic cost and reaction time. Antioxidant assays of the peptide fraction obtained under the optimal conditions proved the high metal-chelating activity preservation (EC50 = 247 ± 27 µg) for more than three times faster production. This fraction might counteract lipid oxidation or serve as preventing agents for micronutrient deficiencies, and the resulting purified napins may have applications in food safety against microbial contamination. These results can greatly help the development of rapeseed meal applications in food industries.

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Iavorschi, Monica, Ancuța-Veronica Lupăescu, Laura Darie-Ion, Maria Indeykina, Gabriela Elena Hitruc e Brîndușa Alina Petre. "Cu and Zn Interactions with Peptides Revealed by High-Resolution Mass Spectrometry". Pharmaceuticals 15, n. 9 (31 agosto 2022): 1096. http://dx.doi.org/10.3390/ph15091096.

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Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by abnormal extracellular amyloid-beta (Aβ) peptide depositions in the brain. Among amorphous aggregates, altered metal homeostasis is considered a common risk factor for neurodegeneration known to accelerate plaque formation. Recently, peptide-based drugs capable of inhibiting amyloid aggregation have achieved unprecedented scientific and pharmaceutical interest. In response to metal ions binding to Aβ peptide, metal chelation was also proposed as a therapy in AD. The present study analyzes the interactions formed between NAP octapeptide, derived from activity-dependent neuroprotective protein (ADNP), amyloid Aβ(9-16) fragment and divalent metal ions such as Cu and Zn. The binding affinity studies for Cu and Zn ions of synthetic NAP peptide and Aβ(9-16) fragment were investigated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), electrospray ion trap mass spectrometry (ESI-MS) and atomic force microscopy (AFM). Both mass spectrometric methods confirmed the formation of metal–peptide complexes while the AFM technique provided morphological and topographic information regarding the influence of metal ions upon peptide crystallization. Our findings showed that due to a rich histidine center, the Aβ(9-16) fragment is capable of binding metal ions, thus becoming stiff and promoting aggregation of the entire amyloid peptide. Apart from this, the protective effect of the NAP peptide was found to rely on the ability of this octapeptide to generate both chelating properties with metals and interactions with Aβ peptide, thus stopping its folding process.

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Lachowicz, Joanna Izabela, Gabriele Dalla Torre, Rosita Cappai, Enrico Randaccio, Valeria M. Nurchi, Remigiusz Bachor, Zbigniew Szewczuk et al. "Metal self-assembly mimosine peptides with enhanced antimicrobial activity: towards a new generation of multitasking chelating agents". Dalton Transactions 49, n. 9 (2020): 2862–79. http://dx.doi.org/10.1039/c9dt04545g.

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Famuwagun, Akinsola A., Adeola M. Alashi, Saka O. Gbadamosi, Kehinde A. Taiwo, Durodoluwa Oyedele, Odunayo C. Adebooye e Rotimi E. Aluko. "Effect of Protease Type and Peptide Size on the In Vitro Antioxidant, Antihypertensive and Anti-Diabetic Activities of Eggplant Leaf Protein Hydrolysates". Foods 10, n. 5 (18 maggio 2021): 1112. http://dx.doi.org/10.3390/foods10051112.

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Solanum macrocarpon (eggplant) leaf protein isolate (ELI) was hydrolyzed using four different enzymes to produce hydrolysates from alcalase (AH), chymotrypsin (CH) pepsin (PH) and trypsin (TH). CH had an overall stronger antioxidant property and was separated using ultrafiltration membranes into <1, 1–3 and 3–5 kDa peptide fractions. Gel-permeation chromatography confirmed conversion of the ELI (average of 22 kDa) into protein hydrolysates that contained smaller peptides (<6 kDa). A total of 23 peptides consisting of tri and tetrapeptides were identified from the CH, which is a wider spectrum when compared to seven for AH and four each for TH and PH. CH exhibited stronger scavenging activities against DPPH and hydroxyl radicals. CH and TH exhibited the strongest inhibitions against angiotensin-converting enzyme. In contrast, AH was the strongest inhibitor of α-amylase while AH and PH had strong inhibitory activities against α-glucosidase when compared with other hydrolysates. Ultrafiltration fractionation produced peptides that were stronger (p < 0.05) scavengers of DPPH, and hydroxyl radicals, in addition to better metal-chelating and enzyme inhibition agents. The study concluded that the eggplant protein hydrolysates and the UF fractions may find applications in tackling oxidative stress-related diseases and conditions involving excessive activities of the metabolic enzymes.

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Thompson, Channing C., e Rebecca Y. Lai. "Threonine Phosphorylation of an Electrochemical Peptide-Based Sensor to Achieve Improved Uranyl Ion Binding Affinity". Biosensors 12, n. 11 (2 novembre 2022): 961. http://dx.doi.org/10.3390/bios12110961.

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We have successfully designed a uranyl ion (U(VI)-specific peptide and used it in the fabrication of an electrochemical sensor. The 12-amino acid peptide sequence, (n) DKDGDGYIpTAAE (c), originates from calmodulin, a Ca(II)-binding protein, and contains a phosphothreonine that enhances the sequence’s affinity for U(VI) over Ca(II). The sensing mechanism of this U(VI) sensor is similar to other electrochemical peptide-based sensors, which relies on the change in the flexibility of the peptide probe upon interacting with the target. The sensor was systematically characterized using alternating current voltammetry (ACV) and cyclic voltammetry. Its limit of detection was 50 nM, which is lower than the United States Environmental Protection Agency maximum contaminant level for uranium. The signal saturation time was ~40 min. In addition, it showed minimal cross-reactivity when tested against nine different metal ions, including Ca(II), Mg(II), Pb(II), Hg(II), Cu(II), Fe(II), Zn(II), Cd(II), and Cr(VI). Its reusability and ability to function in diluted aquifer and drinking water samples were further confirmed and validated. The response of the sensor fabricated with the same peptide sequence but with a nonphosphorylated threonine was also analyzed, substantiating the positive effects of threonine phosphorylation on U(VI) binding. This study places emphasis on strategic utilization of non-standard amino acids in the design of metal ion-chelating peptides, which will further diversify the types of peptide recognition elements available for metal ion sensing applications.

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Shu, Guowei, Zhuo Wang, Li Chen, Qian Zhang e Ni Xin. "Enzymolysis Technology Optimization for Production of Antioxidant Peptides from Goat Milk Casein". Acta Universitatis Cibiniensis. Series E: Food Technology 21, n. 1 (1 giugno 2017): 51–60. http://dx.doi.org/10.1515/aucft-2017-0006.

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AbstractAntioxidant peptides can inhibit lipid peroxidation and scavenging free radicals, maintain the balance of free radicals, and against a variety of diseases. Response surface methodology was used to optimize process conditions for producing antioxidative peptides from goat’s milk casein hydrolysate with Alcalase. The results suggested that the optimal process parameters were: temperature at 62.5°C, pH 8.9, E/S ration at 2.5%, substrate concentration at 4.4% and hydrolysis time was 173min). Metal-chelating effect, superoxide anion radical scavenging activity and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity were shown to be 87.21±0.88%, 49.18±1.42% and 69.07±1.26% respectively under the optimal condition. The actual and predicated value were closely which indicated the optimized data fit well to model and the optimized parameters are reliable.

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Zhang, Bin, Zhou-rong Shi, Xiao-ling Wang, Shang-gui Deng e Hui-min Lin. "Depuration of cadmium from blue mussel (Mytilus edulis) by hydrolysis peptides and chelating metal elements". Food Research International 73 (luglio 2015): 162–68. http://dx.doi.org/10.1016/j.foodres.2014.12.043.

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Mutoh, Norihiro, Masao Kawabata e Yukimasa Hayashi. "Tetramethylthiuram disulfide or dimethyldithiocarbamate induces the synthesis of cadystins, heavy metal chelating peptides, in Schizosaccharomyces pombe". Biochemical and Biophysical Research Communications 176, n. 3 (maggio 1991): 1068–73. http://dx.doi.org/10.1016/0006-291x(91)90392-k.

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López-García, Guadalupe, Octavio Dublan-García, Daniel Arizmendi-Cotero e Leobardo Manuel Gómez Oliván. "Antioxidant and Antimicrobial Peptides Derived from Food Proteins". Molecules 27, n. 4 (16 febbraio 2022): 1343. http://dx.doi.org/10.3390/molecules27041343.

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Abstract (sommario):

Recently, the demand for food proteins in the market has increased due to a rise in degenerative illnesses that are associated with the excessive production of free radicals and the unwanted side effects of various drugs, for which researchers have suggested diets rich in bioactive compounds. Some of the functional compounds present in foods are antioxidant and antimicrobial peptides, which are used to produce foods that promote health and to reduce the consumption of antibiotics. These peptides have been obtained from various sources of proteins, such as foods and agri-food by-products, via enzymatic hydrolysis and microbial fermentation. Peptides with antioxidant properties exert effective metal ion (Fe2+/Cu2+) chelating activity and lipid peroxidation inhibition, which may lead to notably beneficial effects in promoting human health and food processing. Antimicrobial peptides are small oligo-peptides generally containing from 10 to 100 amino acids, with a net positive charge and an amphipathic structure; they are the most important components of the antibacterial defense of organisms at almost all levels of life—bacteria, fungi, plants, amphibians, insects, birds and mammals—and have been suggested as natural compounds that neutralize the toxicity of reactive oxygen species generated by antibiotics and the stress generated by various exogenous sources. This review discusses what antioxidant and antimicrobial peptides are, their source, production, some bioinformatics tools used for their obtainment, emerging technologies, and health benefits.

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Fashakin, Olumide Oluwatoyosi, Pipat Tangjaidee, Kridsada Unban, Wannaporn Klangpetch, Tabkrich Khumsap, Korawan Sringarm, Saroat Rawdkuen e Suphat Phongthai. "Isolation and Identification of Antioxidant Peptides Derived from Cricket (Gryllus bimaculatus) Protein Fractions". Insects 14, n. 8 (29 luglio 2023): 674. http://dx.doi.org/10.3390/insects14080674.

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Crickets contain high protein content that can be used to improve nutrition but are less exploited. This study was conducted to isolate different Cricket Protein Fractions including albumin, globulin, glutelin, and prolamin. All fractions were characterized and hydrolyzed by commercial enzymes. The results showed that the glutelin fractions had the highest extraction yields with 53.9 ± 2.12% (p < 0.05). Moreover, glutelin hydrolysate fraction prepared by Alcalase with a 16.35 ±0.29% hydrolysis degree was selected for further purification because of their high antioxidant activities, including ABTS radical-scavenging activity (0.44–0.55 µmol Trolox eq./g) and metal chelating activity (1721.99–1751.71 µmol EDTA eq./g). Two active fractions, GA-1 (<3 kDa) and GA-2 (<3 kDa), were collected from the consecutive purification of glutelin hydrolysates, which included processes such as membrane ultrafiltration and gel filtration. The fractions were analyzed by LC-MS/MS to obtain 10 peptides with 3–13 amino acids identified as TEAPLNPK, EVGA, KLL, TGNLPGAAHPLLL, AHLLT, LSPLYE, AGVL, VAAV, VAGL, and QLL with a molecular weight range of 359.23–721.37 Da in the two fractions. The amino acid sequence shows a prevalence of hydrophobic amino acids (50–100%) such as valine and leucine in the peptide chains, accounting for its high antioxidant activity. In conclusion, cricket glutelin hydrolysate prepared by Alcalase can serve as an alternative source of potent edible bioactive peptides in functional food products.

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Speiser, D. M., D. F. Ortiz, L. Kreppel, G. Scheel, G. McDonald e D. W. Ow. "Purine biosynthetic genes are required for cadmium tolerance in Schizosaccharomyces pombe". Molecular and Cellular Biology 12, n. 12 (dicembre 1992): 5301–10. http://dx.doi.org/10.1128/mcb.12.12.5301-5310.1992.

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Phytochelatins (PCs) are metal-chelating peptides produced in plants and some fungi in response to heavy metal exposure. A Cd-sensitive mutant of the fission yeast Schizosaccharomyces pombe, defective in production of a PC-Cd-sulfide complex essential for metal tolerance, was found to harbor mutations in specific genes of the purine biosynthetic pathway. Genetic analysis of the link between metal complex accumulation and purine biosynthesis enzymes revealed that genetic lesions blocking two segments of the pathway, before and after the IMP branchpoint, are required to produce the Cd-sensitive phenotype. The biochemical functions of these two segments of the pathway are similar, and a model based on the alternate use of a sulfur analog substrate is presented. The novel participation of purine biosynthesis enzymes in the conversion of the PC-Cd complex to the PC-Cd-sulfide complex in the fission yeast raises an intriguing possibility that these same enzymes might have a role in sulfur metabolism in the fission yeast S. pombe, and perhaps in other biological systems.

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Speiser, D. M., D. F. Ortiz, L. Kreppel, G. Scheel, G. McDonald e D. W. Ow. "Purine biosynthetic genes are required for cadmium tolerance in Schizosaccharomyces pombe." Molecular and Cellular Biology 12, n. 12 (dicembre 1992): 5301–10. http://dx.doi.org/10.1128/mcb.12.12.5301.

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Abstract (sommario):

Phytochelatins (PCs) are metal-chelating peptides produced in plants and some fungi in response to heavy metal exposure. A Cd-sensitive mutant of the fission yeast Schizosaccharomyces pombe, defective in production of a PC-Cd-sulfide complex essential for metal tolerance, was found to harbor mutations in specific genes of the purine biosynthetic pathway. Genetic analysis of the link between metal complex accumulation and purine biosynthesis enzymes revealed that genetic lesions blocking two segments of the pathway, before and after the IMP branchpoint, are required to produce the Cd-sensitive phenotype. The biochemical functions of these two segments of the pathway are similar, and a model based on the alternate use of a sulfur analog substrate is presented. The novel participation of purine biosynthesis enzymes in the conversion of the PC-Cd complex to the PC-Cd-sulfide complex in the fission yeast raises an intriguing possibility that these same enzymes might have a role in sulfur metabolism in the fission yeast S. pombe, and perhaps in other biological systems.

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Floresta, Giuseppe, George P. Keeling, Siham Memdouh, Levente K. Meszaros, Rafael T. M. de Rosales e Vincenzo Abbate. "NHS-Functionalized THP Derivative for Efficient Synthesis of Kit-Based Precursors for 68Ga Labeled PET Probes". Biomedicines 9, n. 4 (1 aprile 2021): 367. http://dx.doi.org/10.3390/biomedicines9040367.

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Hexadentate tris(3,4-hydroxypyridinone) ligands (THP) complex Fe3+ at very low iron concentrations and their high affinities for oxophilic trivalent metal ions have led to their development for new applications as bifunctional chelators for the radiometal gallium-68 (68Ga). THP-peptide bioconjugates rapidly and quantitatively complex 68Ga at room temperature, neutral pH, and micromolar ligand concentrations, making them amenable to kit-based radiosynthesis of 68Ga PET radiopharmaceuticals. With the aim to produce an N-hydroxysuccinimide-(NHS)-THP reagent for kit-based 68Ga-labeling and PET imaging, THP-derivatives were designed and synthesized to exploit the advantages of NHS chemistry for coupling with peptides, proteins, and antibodies. The more stable five-carbon atoms linker product was selected for a proof-of-concept conjugation and radiolabeling study with an anti-programmed death ligand 1 (PD-L1) camelid single domain antibody (sdAb) under mild conditions and further evaluated for site-specific amide bond formation with a synthesized glucagon-like peptide-1 (GLP-1) targeting peptide using solid-phase synthesis. The obtained THP-GLP-1 conjugate was tested for its 68Ga chelating ability, demonstrating to be a promising candidate for the detection and monitoring of GLP-1 aberrant malignancies. The obtained sdAb-THP conjugate was radiolabeled with 68Ga under mild conditions, providing sufficient labeling yields after 5 min, demonstrating that the novel NHS-THP bifunctional chelator can be widely used to easily conjugate the THP moiety to different targeting molecules (e.g., antibodies, anticalins, or peptides) under mild conditions, paving the way to the synthesis of different imaging probes with all the advantages of THP radiochemistry.

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McDONNELL, MAEVE, RICHARD FITZGERALD, IDE NI FHAOLÁIN, P. VINCENT JENNINGS e GERARD O'CUINN. "Purification and characterization of aminopeptidase P from Lactococcus lactis subsp. cremoris". Journal of Dairy Research 64, n. 3 (agosto 1997): 399–407. http://dx.doi.org/10.1017/s0022029997002318.

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Aminopeptidase P was purified 65·3-fold from the cytoplasm of Lactococcus lactis subsp. cremoris AM2 with a 5·8% yield. The purified enzyme was found to consist of one polypeptide chain with a relative molecular mass of 41600. Metal chelating agents were found to be inhibitory and Mn2+ and Co2+ stimulated activity 7-fold and 6-fold respectively. The purified enzyme removed the N-terminal amino acid from peptides only where proline (and in one case alanine) was present in the penultimate position. No hydrolysis was observed either with dipeptides even when proline was present in the C-terminal position or when either N-terminal proline or pyroglutamate was present preceding a proline residue in the penultimate position of longer peptides. On the basis of this substrate specificity either aminopeptidase P or post-proline dipeptidyl aminopeptidase are necessary along with a broad specificity aminopeptidase to effect complete hydrolysis of casein-derived peptides containing a single internally placed proline residue. However, both aminopeptidase P and post-proline dipeptidyl aminopeptidase would be required together with a broad specificity aminopeptidase in order to completely hydrolyse casein-derived peptides that contain two internally placed consecutive proline residues. As bitter casein-derived peptides are likely to contain either single prolines or pairs of prolines, aminopeptidase P appears to be an important enzyme for debittering.

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Chikh, Ghania G., Wai Ming Li, Marie-Paule Schutze-Redelmeier, Jean-Claude Meunier e Marcel B. Bally. "Attaching histidine-tagged peptides and proteins to lipid-based carriers through use of metal-ion-chelating lipids". Biochimica et Biophysica Acta (BBA) - Biomembranes 1567 (dicembre 2002): 204–12. http://dx.doi.org/10.1016/s0005-2736(02)00618-1.

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Amoscato, Andrew A., Damon A. Prenovitz e Michael T. Lotze. "Rapid Extracellular Degradation of Synthetic Class I Peptides by Human Dendritic Cells". Journal of Immunology 161, n. 8 (15 ottobre 1998): 4023–32. http://dx.doi.org/10.4049/jimmunol.161.8.4023.

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Abstract Dendritic cells (DCs) effectively process exogenous and endogenous Ag and present peptide in the context of both class I and class II molecules. We have demonstrated that peripheral blood DCs efficiently degrade synthetic class I peptides at their cell surface within minutes as determined by analyzing DC supernatants by HPLC. Fragments were verified as bona fide cleavage products by direct sequencing using collision-induced dissociation tandem mass spectrometry. The predominant degradative activities were 1) not secreted but associated with activity at the plasma membrane, 2) ecto-orientated, 3) not induced by peptide-specific interactions, and 4) not associated with nonspecific uptake. Sequence analysis indicated that both N- and C-terminal as well as endoproteolytic events were occurring at the cell surface. The primary exoproteolytic event was identified as CD13 or CD13-like activity through inhibition studies and could be inhibited by ubiquitin and metal-chelating agents. Endoproteolytic events could be inhibited in the presence of DTT, but the precise nature of this enzyme is still undetermined. Compared with the starting monocyte population, DCs cultured in the presence of granulocyte-macrophage CSF/IL-4 exhibited the highest degradative rate (4.3 nmol/min), followed by cultured monocytes (2.9 nmol/min) and freshly isolated monocytes (1.0 nmol/min). In addition to increased enzymatic activity, a change in substrate specificity was noted. Results are discussed with respect to APC loading, and alternatives are offered for circumventing such degradation.

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Pawlowski, Katharina, Paul Twigg, Svetlana Dobritsa, Changhui Guan e Beth C. Mullin. "A Nodule-Specific Gene Family from Alnus glutinosa Encodes Glycine- and Histidine-Rich Proteins Expressed in the Early Stages of Actinorhizal Nodule Development". Molecular Plant-Microbe Interactions® 10, n. 5 (luglio 1997): 656–64. http://dx.doi.org/10.1094/mpmi.1997.10.5.656.

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Abstract (sommario):

Two cDNAs representing different members (agNt84 and ag164) of a gene family encoding glycine- and histidinerich proteins have been isolated from cDNA libraries from Alnus glutinosa root nodules. Expression of the corresponding genes could only be detected in nodules. With in situ hybridization, the expression in nodules was found to occur in young, infected cells of the prefixation zone (zone 2). The encoded proteins contain putative signal peptides for targeting to the endomembrane system, sharing sequence similarity with signal peptides from plant glycinerich proteins, among them nodulin 24, a nodule-specific protein from soybean. This similarity suggests that, analogous to nodulin-24, proteins encoded by agNt84/ag164 may be located at the interface between the host plant membrane and the matrix surrounding the endosymbiont. The 3′untranslated regions of the cDNAs contain unusual poly(AT)n stretches that may play a role in the regulation of RNA stability. The protein encoded by agNt84 cDNA was expressed in Escherichia coli as a fusion with maltosebinding protein, and was shown to have the ability to bind to a nickel-chelating resin, indicating that it may function as a metal-binding protein.

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Xiao, Chen, Li, He, Cheng e Ren. "In Vitro Antioxidant Activity of Peptides from Simulated Gastro-Intestinal Digestion Products of Cyprinus carpio haematopterus Scale Gelatin". Foods 8, n. 12 (25 novembre 2019): 618. http://dx.doi.org/10.3390/foods8120618.

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Abstract (sommario):

A two-stage simulated gastro-intestinal (GI) digestion model (2 h pepsin treatment and subsequent 2 h pancreatin treatment at 37 °C) was used to explore the antioxidant activity of the digested products of Cyprinus carpio haematopterus scale gelatin with different molecular weights (MW). From the gastric phase to the intestinal phase, the hydrolysis degree of the products increased from 2.6 ± 0.4% to 16.9 ± 0.7%. The fraction of 0–1 kDa (JCP3) exhibited the best antioxidant activities in hydroxyl radical scavenging, reducing power, and metal chelating activity. The fraction of 1–3 kDa (JCP2) exhibited the best 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. However, the fractions of 0–1 kDa (JCP3) and 1–3 kDa (JCP2) showed similar inhibitory activity of lipid peroxidation. The results indicated that Cyprinus carpio haematopterus scale gelatin can be digested in the gastrointestinal tract. Furthermore, the digested products had antioxidant activity.

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Yesiltas, Betül, Pedro J. García-Moreno, Rasmus K. Mikkelsen, Simon Gregersen Echers, Dennis K. Hansen, Mathias Greve-Poulsen, Grethe Hyldig, Egon B. Hansen e Charlotte Jacobsen. "Physical and Oxidative Stability of Emulsions Stabilized with Fractionated Potato Protein Hydrolysates Obtained from Starch Production Side Stream". Antioxidants 12, n. 8 (16 agosto 2023): 1622. http://dx.doi.org/10.3390/antiox12081622.

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This work studies the emulsifying and antioxidant properties of potato protein hydrolysates (PPHs) fractions obtained through enzymatic hydrolysis of potato protein using trypsin followed by ultrafiltration. Unfractionated (PPH1) and fractionated (PPH2 as >10 kDa, PPH3 as 10–5 kDa, PPH4 as 5–0.8 kDa, and PPH5 as <0.8 kDa) protein hydrolysates were evaluated. Pendant drop tensiometry and dilatational rheology were applied for determining the ability of PPHs to reduce interfacial tension and affect the viscoelasticity of the interfacial films at the oil–water interface. Peptides >10 kDa showed the highest ability to decrease oil–water interfacial tension. All PPH fractions predominantly provided elastic, weak, and easily stretchable interfaces. PPH2 provided a more rigid interfacial layer than the other hydrolysates. Radical scavenging and metal chelating activities of PPHs were also tested and the highest activities were provided by the unfractionated hydrolysate and the fractions with peptides >5 kDa. Furthermore, the ability of PPHs to form physically and oxidatively stable 5% fish oil-in-water emulsions (pH 7) was investigated during 8-day storage at 20 °C. Our results generally show that the fractions with peptides >5 kDa provided the highest physicochemical stability, followed by the fraction with peptides between 5 and 0.8 kDa. Lastly, promising sensory results with mostly mild attributes were obtained even at protein concentration levels that are higher than needed to obtain functional properties. The more prominent attributes (e.g., bitterness and astringency) were within an acceptable range for PPH3 and PPH4.

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Remelli, Maurizio, Valeria M. Nurchi, Joanna I. Lachowicz, Serenella Medici, M. Antonietta Zoroddu e Massimiliano Peana. "Competition between Cd(II) and other divalent transition metal ions during complex formation with amino acids, peptides, and chelating agents". Coordination Chemistry Reviews 327-328 (novembre 2016): 55–69. http://dx.doi.org/10.1016/j.ccr.2016.07.004.

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