Journal articles: 'Amino acid- based systems'

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Carrera, Gonçalo V. S. M., Noémi Jordão, Miguel M. Santos, Manuel Nunes da Ponte, and Luís C. Branco. "Reversible systems based on CO2, amino-acids and organic superbases." RSC Advances 5, no. 45 (2015): 35564–71. http://dx.doi.org/10.1039/c5ra03474d.

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Chiral amino-acids in the presence of an organic superbase in a CO₂ atmosphere were used to prepare carbamate-based ionic liquids and molten salts. Variation of the superbase and amino acid R-group gave tuneable CO₂ release temperatures from the products.

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Hu, Weikang, Mei Ying, Shengmin Zhang, and Jianglin Wang. "Poly(amino acid)-Based Carrier for Drug Delivery Systems." Journal of Biomedical Nanotechnology 14, no. 8 (August 1, 2018): 1359–74. http://dx.doi.org/10.1166/jbn.2018.2590.

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Thompson, Marisa, and Carmen Scholz. "Highly Branched Polymers Based on Poly(amino acid)s for Biomedical Application." Nanomaterials 11, no. 5 (April 26, 2021): 1119. http://dx.doi.org/10.3390/nano11051119.

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Polymers consisting of amino acid building blocks continue to receive consideration for biomedical applications. Since poly(amino acid)s are built from natural amino acids, the same building blocks proteins are made of, they are biocompatible, biodegradable and their degradation products are metabolizable. Some amino acids display a unique asymmetrical AB2 structure, which facilitates their ability to form branched structures. This review compares the three forms of highly branched polymeric structures: structurally highly organized dendrimers, dendrigrafts and the less organized, but readily synthesizable hyperbranched polymers. Their syntheses are reviewed and compared, methods of synthesis modulations are considered and variations on their traditional syntheses are shown. The potential use of highly branched polymers in the realm of biomedical applications is discussed, specifically their applications as delivery vehicles for genes and drugs and their use as antiviral compounds. Of the twenty essential amino acids, L-lysine, L-glutamic acid, and L-aspartic acid are asymmetrical AB2 molecules, but the bulk of the research into highly branched poly(amino acid)s has focused on the polycationic poly(L-lysine) with a lesser extent on poly(L-glutamic acid). Hence, the majority of potential applications lies in delivery systems for nucleic acids and this review examines and compares how these three types of highly branched polymers function as non-viral gene delivery vectors. When considering drug delivery systems, the small size of these highly branched polymers is advantageous for the delivery of inhalable drug. Even though highly branched polymers, in particular dendrimers, have been studied for more than 40 years for the delivery of genes and drugs, they have not translated in large scale into the clinic except for promising antiviral applications that have been commercialized.

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Steczko, J., K. C. Bax, and S. R. Ash. "Effect of Hemodiabsorption and Sorbent-Based Pheresis on Amino Acid Levels in Hepatic Failure." International Journal of Artificial Organs 23, no. 6 (June 2000): 375–88. http://dx.doi.org/10.1177/039139880002300606.

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Changes in plasma amino acid concentrations were measured in patients with hepatic failure during extracorporeal hemodiabsorption (using the Liver Dialysis Unit, “the Unit”) or hemodiabsorption plus sorbent-based pheresis treatment (using the Liver Dialysis Plasmafilter Unit, “the PF-Unit”) Systems. Eight patients with hepatic failure, grade 3 or 4 encephalopathy, elevated bilirubin and/or creatinine levels and respiratory or renal failure were treated for 1–3 days with the Unit alone. Three of these were also treated with the Unit containing 10 g of BCAA in the sorbent suspension. Four patients with hepatic failure treated with the PF Unit also had 10 g of branched chain amino acid (BCAA) added to the sorbents of the Unit portion of this device. Pre- and post-plasma samples were drawn and high performance liquid chromatography (HPLC) was used to separate and detect amino acids in the plasma. Both the Unit and the PF-Unit have the capability to selectively remove various amino acids, especially aromatic amino acids (AAA). The pre-treatment amino acid profiles of plasma were typical for hepatic failure, with abnormally high levels of phenylalanine, tyrosine, tryptophan, and methionine and decreased levels of valine, leucine and isolucine. The average pre-treatment Fischer ratio (BCAA/AAA) for both Unit and PF-Unit patients was 1.43 (±0.58). Treatments by both systems resulted in an increase of BCAA levels in blood and concomitant decrease of AAA levels, with an average Fischer ratio improvement of 30–38% for the Unit and PF-Unit without BCAA. The Fischer ratio improved by 90% (average) for the Unit with BCAA. Levels of many other amino acids (such as alanine, glycine, proline or lysine) increased during both Unit and PF-Unit treatments. The removal of strongly protein-bound toxin and amino acids such as tryptophan and sulphydryl amino acids was more effective by the PF-Unit. Both the Unit and the PF-Unit have the unique capability to remove toxic aromatic amino acids while increasing BCAA levels in patient. The increase in many amino acid levels may be related to the removal of toxins that interfere with normal amino acid metabolism. The addition of the PF module improves the removal of bilirubin and similarly protein-bound chemicals. Changes in amino acid profiles by the Unit and the PF-Unit contrast markedly with other extracorporeal devices.

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Bartlett, Stacey, Mariusz Skwarczynski, Xin Xie, Istvan Toth, Alex Loukas, and Ramon M. Eichenberger. "Development of natural and unnatural amino acid delivery systems against hookworm infection." Precision Nanomedicine 3, no. 1 (January 30, 2020): 471–82. http://dx.doi.org/10.33218/prnano3(1).191210.1.

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Peptide-based vaccines consist of short antigen fragments derived from a specific pathogen. Alone, these peptide fragments are poorly or non-immunogenic; however, when incorporated into a proper delivery system, they can trigger strong immune responses. To eliminate the need for toxic and often ineffective oral adjuvants, we designed single molecule-based self-adjuvating vaccines against hookworms using natural and unnatural hydrophobic amino acids. Two vaccine conjugates were synthesized, consisting of B-cell epitope p3, derived from the hookworm Na-APR-1 protein; universal T-helper peptide P25; and either double copies of unnatural lipoamino acid (2-amino-D,L-eicosanoic acid), or ten copies of the natural amino acid leucine. After challenge with the model hookworm, Nippostrongylus brasiliensis, mice orally immunized with the conjugates, but without adjuvant, generated antibody responses against the hookworm epitope, resulting in significantly reduced worm and egg burdens compared to control mice. We have demonstrated that vaccine nanoparticles composed exclusively of natural amino acids can be effective even when administered orally.

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Stücheli, Patrick E., Thomas Larsen, Bernhard Wehrli, and Carsten J. Schubert. "Amino acid and chlorin based degradation indicators in freshwater systems." Geochimica et Cosmochimica Acta 304 (July 2021): 216–33. http://dx.doi.org/10.1016/j.gca.2021.04.006.

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Chican, I. E., D. Vărăşteanu, I. Fierăscu, R. C. Fierăscu, and M. Deaconu. "Surface properties in surfactant systems containing amino acid-based surfactants." IOP Conference Series: Materials Science and Engineering 572 (August 2, 2019): 012009. http://dx.doi.org/10.1088/1757-899x/572/1/012009.

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Abbas, Sam H., and Dirk Schulze-Makuch. "Amino acid synthesis in Europa's subsurface environment." International Journal of Astrobiology 7, no. 3-4 (October 2008): 193–203. http://dx.doi.org/10.1017/s1473550408004114.

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AbstractIt has been suggested that Europa's subsurface environment may provide a haven for prebiotic evolution and the development of exotic biotic systems. The detection of hydrogen peroxide, sulfuric acid, water, hydrates and related species on the surface, coupled with observed mobility of icebergs, suggests the presence of a substantial subsurface liquid reservoir that actively exchanges materials with the surface environment. The atmospheric, surface and subsurface environments are described with their known chemistry. Three synthetic schemes using hydrogen peroxide, sulfuric acid and hydrocyanic acid leading to the production of larger biologically important molecules such as amino acids are described. Metabolic pathways based on properties of the subsurface ocean environment are detailed. Tidal heating, osmotic gradients, chemical cycling, as well as hydrothermal vents, provide energy and materials that may support a course of prebiotic evolution leading to the development or sustenance of simple biotic systems. Putative organisms may employ metabolic pathways based on chemical oxidation–reduction cycles occurring in the putative subsurface ocean environment.

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Mokshina, Nadezhda Ya, Oksana A. Pakhomova, Gennadiy V. Shatalov, and Irina I. Kosinova. "INTERPHASE DISTRIBUTION OF SOME AMINO ACIDS IN EXTRACTION SYSTEMS BASED ON N-VINYLFORMAMIDE COPOLYMERS." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, no. 1 (January 10, 2019): 4–10. http://dx.doi.org/10.6060/ivkkt.20196201.5763.

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The extraction characteristics of amino acids and mono-amides of acids were studied using copolymers of N-vinylformamide with 1-vinyl- and 1-methacryloyl-3,5-dimethylpyrazole as extractants. Synthesis of water-soluble copolymers was carried out by radical copolymerization in dioxane with thermoinitiation with dinitro-azobisisomoic acid. The distribution coefficients and the degree of extraction of analytes for a single extraction in the presence of a salting out agent are calculated. To determine the representatives of amino acids, the method of capillary electrophoresis was used. The most effective extraction systems for the extraction of amino acids and monoamides of acids are proposed: the intrinsic viscosity of polymers, the concentration of polymer and analyte solution, the ratio of phase volumes, the ratio of the mole fractions of N-vinylformamide to 1-vinyl and 1-methacryloyl-3,5-dimethylpyrazole. The results of the most effective interfacial distribution of lysine between a water-salt solution and an extractant are presented, which is a copolymer of N-vinylformamide with 1-methacryloyl-3,5-dimethylpyrazole. The concentration of the copolymer and the ratio of the volumes of equilibrium phases at which the maximum degree of lysine extraction is reached are established. A copolymer of N-vinylformamide with 1-vinyl-3,5-dimethylpyrazole is used for simultaneous extraction of cystine, asparagine and glutamine. The established extraction characteristics allowed a successful separate determination of the amino acid cystine and monoamides (asparagine and glutamine) in a joint presence in an aqueous solution. When choosing the conditions for separate electrophoretic determination of amino acids, the optimal composition of the buffer solution, the type and concentration of the micelle was found. The dependence of the structure of the analytes on their interphase distribution was established, and the complexing power of the copolymers of N-vinylformamide with 1-vinyl- and 1-methacryloyl-3,5-dimethylpyrazole was revealed with respect to the representatives of amino acids. The extraction systems used on the basis of N-vinylformamide copolymers are distinguished by ecological and economic expediency, good metrological indices.

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Shrestha, Rekha Goswami, Lok Kumar Shrestha, and Kenji Aramaki. "Wormlike micelles in mixed amino acid-based anionic/nonionic surfactant systems." Journal of Colloid and Interface Science 322, no. 2 (June 2008): 596–604. http://dx.doi.org/10.1016/j.jcis.2008.03.009.

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Geidenstam, Nina, Martin Magnusson, Anders P. H. Danielsson, Robert E. Gerszten, Thomas J. Wang, Lovisa E. Reinius, Hindrik Mulder, Olle Melander, and Martin Ridderstråle. "Amino Acid Signatures to Evaluate the Beneficial Effects of Weight Loss." International Journal of Endocrinology 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/6490473.

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Aims. We investigated the relationship between circulating amino acid levels and obesity; to what extent weight loss followed by weight maintenance can correct amino acid abnormalities; and whether amino acids are related to weight loss.Methods. Amino acids associated with waist circumference (WC) and BMI were studied in 804 participants from the Malmö Diet and Cancer Cardiovascular Cohort (MDC-CC). Changes in amino acid levels were analyzed after weight loss and weight maintenance in 12 obese subjects and evaluated in a replication cohort (n=83).Results. Out of the eight identified BMI-associated amino acids from the MDC-CC, alanine, isoleucine, tyrosine, phenylalanine, and glutamate decreased after weight loss, while asparagine increased after weight maintenance. These changes were validated in the replication cohort. Scores that were constructed based on obesity-associated amino acids and known risk factors decreased in the ≥10% weight loss group with an associated change in BMI (R2=0.16–0.22,p<0.002), whereas the scores increased in the <10% weight loss group (p<0.0004).Conclusions. Weight loss followed by weight maintenance leads to differential changes in amino acid levels associated with obesity. Treatment modifiable scores based on epidemiological and interventional data may be used to evaluate the potential metabolic benefit of weight loss.

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Kumar, D. "Apparent molar volume of some ω-amino acids in aqueous electrolyte systems." Canadian Journal of Chemistry 77, no. 7 (July 1, 1999): 1288–94. http://dx.doi.org/10.1139/v99-117.

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Apparent molar volumes (Vϕ) of some ω-amino acids have been determined in aqueous guanidine hydrochloride (6 m GuHCl) and sodium sulphate (2 m Na2SO4) solutions at 288.15 and 298.15 K using a vibrating tube digital densimeter. The transfer volumes of amino acids from water to aqueous electrolyte systems have been reported. The transfer properties are interpreted in terms of strong interactions, based on a cosphere overlap model of guanidine hydrochloride/sodium sulphate molecules with the charged centers of the zwitterions (amino acid molecules), as compared to ion - nonpolar group interactions.Key words: amino acids, denaturation, guanidine hydrochloride, sodium sulphate, apparent molar volume, zwitterions, limiting apparent molar volume.

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Requejo, Patricia F., Elena Gómez, and Eugénia A. Macedo. "Partitioning of DNP-Amino Acids in New Biodegradable Choline Amino Acid/Ionic Liquid-Based Aqueous Two-Phase Systems." Journal of Chemical & Engineering Data 64, no. 11 (May 8, 2019): 4733–40. http://dx.doi.org/10.1021/acs.jced.9b00052.

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Ossowicz-Rupniewska, Paula, Rafał Rakoczy, Anna Nowak, Maciej Konopacki, Joanna Klebeko, Ewelina Świątek, Ewa Janus, et al. "Transdermal Delivery Systems for Ibuprofen and Ibuprofen Modified with Amino Acids Alkyl Esters Based on Bacterial Cellulose." International Journal of Molecular Sciences 22, no. 12 (June 10, 2021): 6252. http://dx.doi.org/10.3390/ijms22126252.

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The potential of bacterial cellulose as a carrier for the transport of ibuprofen (a typical example of non-steroidal anti-inflammatory drugs) through the skin was investigated. Ibuprofen and its amino acid ester salts-loaded BC membranes were prepared through a simple methodology and characterized in terms of structure and morphology. Two salts of amino acid isopropyl esters were used in the research, namely L-valine isopropyl ester ibuprofenate ([ValOiPr][IBU]) and L-leucine isopropyl ester ibuprofenate ([LeuOiPr][IBU]). [LeuOiPr][IBU] is a new compound; therefore, it has been fully characterized and its identity confirmed. For all membranes obtained the surface morphology, tensile mechanical properties, active compound dissolution assays, and permeation and skin accumulation studies of API (active pharmaceutical ingredient) were determined. The obtained membranes were very homogeneous. In vitro diffusion studies with Franz cells were conducted using pig epidermal membranes, and showed that the incorporation of ibuprofen in BC membranes provided lower permeation rates to those obtained with amino acids ester salts of ibuprofen. This release profile together with the ease of application and the simple preparation and assembly of the drug-loaded membranes indicates the enormous potentialities of using BC membranes for transdermal application of ibuprofen in the form of amino acid ester salts.

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Koverda, Anna A., Alexandra I. Korshunova, Mikhail N. Koverda, and Evgeny N. Sechin. "Synthesis of monomers for the preparation of optically active poly(amido–imide)s. Part 1. Synthesis of chiral imides containing a fragment of the natural amino acid based on nitrophenylcycloalkanedicarboxylic acids." Butlerov Communications 57, no. 1 (January 31, 2019): 27–40. http://dx.doi.org/10.37952/roi-jbc-01/19-57-1-27.

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Previously it was shown that the stereochemical result of the alkylation reaction of benzene with cycloalkanedicarboxylic acids depends on the order of mixing the reagents. The resulting diastereomerically pure derivatives can be used as precursors of monomers for the synthesis of optically active poly(amido–imide)s, which are basic materials in chiral chromatographic separation. Their potential for use in chiral catalytic systems, liquid crystals in ferroelectric and nonlinear optics, in the manufacture of electrodes for enantioselective recognition during bioelectrosynthesis, membrane separation technology, etc. is shown. Nitration reactions of alkyl derivatives were carried out with their subsequent imidization with natural amino acids. The resulting diastereomerically pure dicarboxylic acids are nitrated with low selectivity, unlike their anhydrides, so the nitro derivatives were synthesized by nitrating the anhydrides with anhydrous nitric acid in chloroform solution. The racemization of the α-carbon center of the amino acid fragment occurs during the imidization reaction in glacial acetic acid. Using of DMF as a solvent under mild conditions is preferable, as it eliminates the possibility of racemization of the chiral center of the amino acid fragment. It was also found that during the preparation of imides, the configuration of the chiral centers of the cycloalkane dicarboxylic acid fragment is preserved. Nitrophenylnorbornanedicarboxylic acid forms an anhydride directly during synthesis in acetic acid, unlike cyclohexanedicarboxylic acids, due to its spatial structure. Nitrophenylnorbornanedicarboxylic acid is also characterized by easier imidization. The structure was determined using 1H, 13C NMR, 1H-1H NOESY, 1H-1H COSY, HPLC, capillary electrophoresis.

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Liu, Jingwen, Thomas Rades, and Holger Grohganz. "Determination of the Optimal Molar Ratio in Amino Acid-Based Coamorphous Systems." Molecular Pharmaceutics 17, no. 4 (March 2, 2020): 1335–42. http://dx.doi.org/10.1021/acs.molpharmaceut.0c00042.

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Correa, Andrea, Michele Cascella, Nicola Scotti, Federica Zaccheria, Nicoletta Ravasio, and Rinaldo Psaro. "Mechanistic insights into formic acid dehydrogenation promoted by Cu-amino based systems." Inorganica Chimica Acta 470 (January 2018): 290–94. http://dx.doi.org/10.1016/j.ica.2017.06.043.

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Kolver, Eric S. "Nutritional limitations to increased production on pasture-based systems." Proceedings of the Nutrition Society 62, no. 2 (May 2003): 291–300. http://dx.doi.org/10.1079/pns2002200.

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The constraints to high levels of milk production imposed by a high-quality-pasture diet, and development of feeding strategies to overcome these limitations, were examined by modelling the nutritional status of New Zealand Friesian and North American Holstein–Friesian dairy cows grazing high-quality pasture. The Cornell Net Carbohydrate and Protein System (CNCPS) was used to predict sensitivity of milk production to a 10 % change in the composition of pasture nutrients. The rate at which fibre and protein were degraded in the rumen and the value given to effective fibre and lignin content significantly affected the supply of metabolisable energy and protein, and the profile of amino acid supply. The first limiting factor in milk production when only high-quality pasture was fed was metabolisable energy supply, while specific amino acids, particularly methionine and lysine, limited milk production when > 20 g/kg diet consisted of a grain supplement. Compared with cows fed a total mixed ration in confinement, North American Holstein–Friesians grazing all pasture produced less milk (29.6 v. 44.1 kg/d). Of the difference in milk production 61 % could be attributed to a lower DM intake (19 kg/d v. 23.4 kg/d). Predictions using the CNCPS indicated that supply of metabolisable energy was the first-limiting factor for milk production from high-quality pasture (251 g crude protein (N× 6.25)/kg, 432 g neutraldetergent fibre/kg, 77 % in vitro DM digestibility), rather than metabolisable protein or amino acids. In addition, these nutritional limitations imposed by pasture diets will be greater for dairy cow genotypes that have not been selected for high performance within a pasture system.

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Levit, Mariia, Natalia Zashikhina, Alena Vdovchenko, Anatoliy Dobrodumov, Natalya Zakharova, Anna Kashina, Eckart Rühl, et al. "Bio-Inspired Amphiphilic Block-Copolymers Based on Synthetic Glycopolymer and Poly(Amino Acid) as Potential Drug Delivery Systems." Polymers 12, no. 1 (January 10, 2020): 183. http://dx.doi.org/10.3390/polym12010183.

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In this work, a method to prepare hybrid amphiphilic block copolymers consisting of biocompatible synthetic glycopolymer with non-degradable backbone and biodegradable poly(amino acid) (PAA) was developed. The glycopolymer, poly(2-deoxy-2-methacrylamido-D-glucose) (PMAG), was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Two methods for modifying the terminal dithiobenzoate-group of PMAG was investigated to obtain the macroinitiator bearing a primary aliphatic amino group, which is required for ring-opening polymerization of N-carboxyanhydrides of hydrophobic α-amino acids. The synthesized amphiphilic block copolymers were carefully analyzed using a set of different physico-chemical methods to establish their composition and molecular weight. The developed amphiphilic copolymers tended to self-assemble in nanoparticles of different morphology that depended on the nature of the hydrophobic amino acid present in the copolymer. The hydrodynamic diameter, morphology, and cytotoxicity of polymer particles based on PMAG-b-PAA were evaluated using dynamic light scattering (DLS) and transmission electron microscopy (TEM), as well as CellTiter-Blue (CTB) assay, respectively. The redox-responsive properties of nanoparticles were evaluated in the presence of glutathione taken at different concentrations. Moreover, the encapsulation of paclitaxel into PMAG-b-PAA particles and their cytotoxicity on human lung carcinoma cells (A549) and human breast adenocarcinoma cells (MCF-7) were studied.

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WAN, XIANG, THEODORE TEGOS, and GUOHUI LIN. "HISTOGRAM-BASED SCORING SCHEMES FOR PROTEIN NMR RESONANCE ASSIGNMENT." Journal of Bioinformatics and Computational Biology 02, no. 04 (December 2004): 747–64. http://dx.doi.org/10.1142/s0219720004000843.

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In NMR protein structure determination, after the resonance peaks have been identified and chemical shifts from peaks across multiple spectra have been grouped into spin systems, associating these spin systems to their host residues is the key toward the success of structural information extraction and thus the key to the success of the structure calculation. To achieve accurate enough structure calculation, a near complete and accurate assignment is a prerequisite. There are two pieces of information that can be used into the assignment, one of which is the adjacency information among the spin systems and the other is the signature information of the spin systems. The signature information reflects the fact that, generally speaking, for one type of amino acid residing in a specific local structural environment, the chemical shifts for the atoms inside the amino acid fall into some very narrow distinct ranges. In most of the existing work, normal distributions are assumed with means and standard deviations statistically collected from the available data. In this paper, we followed a simple yet effective histogram-based way to estimate for every spin system the probability that its host is a certain type of amino acid residing in a certain type of secondary structure. We used two combinations of chemical shifts to demonstrate the effectiveness of this type of histogram-based scoring schemes.

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Feng, Huayang, Jonas Fabrizi, Jingguo Li, and Christian Mayer. "Syntheses of Polypeptides and Their Biomedical Application for Anti-Tumor Drug Delivery." International Journal of Molecular Sciences 23, no. 9 (May 2, 2022): 5042. http://dx.doi.org/10.3390/ijms23095042.

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Polypeptides have attracted considerable attention in recent decades due to their inherent biodegradability and biocompatibility. This mini-review focuses on various ways to synthesize polypeptides, as well as on their biomedical applications as anti-tumor drug carriers over the past five years. Various approaches to preparing polypeptides are summarized, including solid phase peptide synthesis, recombinant DNA techniques, and the polymerization of activated amino acid monomers. More details on the polymerization of specifically activated amino acid monomers, such as amino acid N-carboxyanhydrides (NCAs), amino acid N-thiocarboxyanhydrides (NTAs), and N-phenoxycarbonyl amino acids (NPCs), are introduced. Some stimuli-responsive polypeptide-based drug delivery systems that can undergo different transitions, including stability, surface, and size transition, to realize a better anti-tumor effect, are elaborated upon. Finally, the challenges and opportunities in this field are briefly discussed.

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Er, Simge, Ushna Laraib, Rabia Arshad, Saman Sargazi, Abbas Rahdar, Sadanand Pandey, Vijay Kumar Thakur, and Ana M. Díez-Pascual. "Amino Acids, Peptides, and Proteins: Implications for Nanotechnological Applications in Biosensing and Drug/Gene Delivery." Nanomaterials 11, no. 11 (November 8, 2021): 3002. http://dx.doi.org/10.3390/nano11113002.

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Over various scientific fields in biochemistry, amino acids have been highlighted in research works. Protein, peptide- and amino acid-based drug delivery systems have proficiently transformed nanotechnology via immense flexibility in their features for attaching various drug molecules and biodegradable polymers. In this regard, novel nanostructures including carbon nanotubes, electrospun carbon nanofibers, gold nanoislands, and metal-based nanoparticles have been introduced as nanosensors for accurate detection of these organic compounds. These nanostructures can bind the biological receptor to the sensor surface and increase the surface area of the working electrode, significantly enhancing the biosensor performance. Interestingly, protein-based nanocarriers have also emerged as useful drug and gene delivery platforms. This is important since, despite recent advancements, there are still biological barriers and other obstacles limiting gene and drug delivery efficacy. Currently available strategies for gene therapy are not cost-effective, and they do not deliver the genetic cargo effectively to target sites. With rapid advancements in nanotechnology, novel gene delivery systems are introduced as nonviral vectors such as protein, peptide, and amino acid-based nanostructures. These nano-based delivery platforms can be tailored into functional transformation using proteins and peptides ligands based nanocarriers, usually overexpressed in the specified diseases. The purpose of this review is to shed light on traditional and nanotechnology-based methods to detect amino acids, peptides, and proteins. Furthermore, new insights into the potential of amino protein-based nanoassemblies for targeted drug delivery or gene transfer are presented.

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Rainey, Jan K., and M. Cynthia Goh. "Statistically Based Reduced Representation of Amino Acid Side Chains‡." Journal of Chemical Information and Computer Sciences 44, no. 3 (May 2004): 817–30. http://dx.doi.org/10.1021/ci034177z.

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Zhu, Zijian, Kai Hu, Siyu Chen, Sirui Xiong, and Yongsheng Tao. "Increase in Fruity Ester Production during Spine Grape Wine Fermentation by Goal-Directed Amino Acid Supplementation." Fermentation 7, no. 4 (October 16, 2021): 231. http://dx.doi.org/10.3390/fermentation7040231.

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The aim of this work was to enhance the levels of fruity esters in spine grape (Vitis davidii Foёx) wine by goal-directed amino acid supplementation during fermentation. HPLC and GC-MS monitored the amino acids and fruity esters, respectively, during alcoholic fermentation of spine grape and Cabernet Sauvignon grape. HPLC was also used to determine the extracellular metabolites and precursors involved in the synthesis of fruity esters. Alanine, phenylalanine, and isoleucine levels in spine grape were less than those in Cabernet Sauvignon. Pearson correlation between amino acid profile and fruity ester content in the two systems indicated that deficiencies in alanine, phenylalanine, and isoleucine levels might have limited fruity ester production in spine grape wine. Supplementation of these three amino acids based on their levels in Cabernet Sauvignon significantly increased fruity ester content in spine grape wine. Interestingly, goal-directed amino acid supplementation might have led to changes in the distribution of carbon fluxes, which contributed to the increase in fruity ester production.

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den Hengst, Chris D., Maarten Groeneveld, Oscar P. Kuipers, and Jan Kok. "Identification and Functional Characterization of the Lactococcus lactis CodY-Regulated Branched-Chain Amino Acid Permease BcaP (CtrA)." Journal of Bacteriology 188, no. 9 (May 1, 2006): 3280–89. http://dx.doi.org/10.1128/jb.188.9.3280-3289.2006.

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ABSTRACT Transcriptome analyses have previously revealed that a gene encoding the putative amino acid transporter CtrA (YhdG) is one of the major targets of the pleiotropic regulator CodY in Lactococcus lactis and Bacillus subtilis. The role of ctrA in L. lactis was further investigated with respect to both transport activity as well as CodY-mediated regulation. CtrA is required for optimal growth in media containing free amino acids as the only amino acid source. Amino acid transport studies showed that ctrA encodes a secondary amino acid transport system that is specific for branched-chain amino acids (BCAAs) (isoleucine, leucine, and valine) and methionine, which is in disagreement with its previously proposed function (a cationic amino acid transporter), which was assigned based on homology. We propose to rename CtrA BcaP, for branched-chain amino acid permease. BcaP is a member of a group of conserved transport systems, as homologs are widely distributed among gram-positive bacteria. Deletion of bcaP resulted in the loss of most of the BCAA uptake activity of L. lactis, indicating that BcaP is the major BCAA carrier of this organism. Deletion of bcaP together with a second (putative) BCAA permease, encoded by brnQ, further reduced the viability of the strain. DNA microarray analysis showed that deletion of bcaP predominantly affects genes belonging to the regulons of the transcriptional regulator CodY, which is involved in global nitrogen metabolism and needs BCAAs for its activation, and of CmbR, which is involved in sulfur amino acid metabolism.

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Carreira, Ana R. F., Samuel N. Rocha, Francisca A. e Silva, Tânia E. Sintra, Helena Passos, Sónia P. M. Ventura, and João A. P. Coutinho. "Amino-acid-based chiral ionic liquids characterization and application in aqueous biphasic systems." Fluid Phase Equilibria 542-543 (August 2021): 113091. http://dx.doi.org/10.1016/j.fluid.2021.113091.

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Lu, Haiwei, Minjia Yuan, Bo Fang, Jinshuang Wang, and Yiguang Guo. "Wormlike Micelles in Mixed Amino Acid-Based Anionic Surfactant and Zwitterionic Surfactant Systems." Journal of Surfactants and Detergents 18, no. 4 (March 27, 2015): 589–96. http://dx.doi.org/10.1007/s11743-015-1683-9.

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Sweed, Ayman M. K., Mathias O. Senge, Sanaa M. Sh Atta, Dalia S. Farrag, Abdel-Rahman H. Abdel-Rahman, and Yasser M. Shaker. "Synthesis of amphiphilic meso-tetrasubstituted porphyrin-L-amino acid and -heterocyclic conjugates based on m-THPP." Journal of Porphyrins and Phthalocyanines 22, no. 11 (October 18, 2018): 997–1009. http://dx.doi.org/10.1142/s1088424618500979.

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Two series of amphiphilic meso-tetrasubstituted porphyrin conjugates based on 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin ([Formula: see text]-THPP) covalently linked to L-amino acids and heterocycles were synthesized efficiently in the context of a program targeting new photosensitizers for PDT. 5,10,15-Tris(3-hydroxyphenyl)-20-(3-oxyacetic acid)phenyl]porphyrin and the respective trihexyl ether derivatives were conjugated with polar and non-polar natural L-amino acids such as glycine, L-proline, and L-tyrosine via an amide bond linker using [Formula: see text]-tetramethyl-[Formula: see text]-(1H-benzotriazol-1-yl)uroniumhexafluorophosphate in diisopropylethylamine (HBTU/DIPEA). [Formula: see text]-THPP was also conjugated with heterocyclic systems such as indole 3-acetic acid, 4-methylthiazole-5-carboxylic acid, and thiophene-2-carboxylic acid via ester linker using [Formula: see text]-(3-dimethylaminopropyl)-[Formula: see text]-ethylcarbodiimide hydrochloride in [Formula: see text]-hydroxysuccinamide or 1-hydroxybenzotriazole (EDCI, NHS or HOBt). The members of the two series were obtained in good yields and characterized by UV-vis, HRMS MALDI-TOF, 1H NMR and 13C NMR spectroscopy.

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Puigmal, Núria, Víctor Ramos, Natalie Artzi, and Salvador Borrós. "Poly(β-amino ester)s-Based Delivery Systems for Targeted Transdermal Vaccination." Pharmaceutics 15, no. 4 (April 17, 2023): 1262. http://dx.doi.org/10.3390/pharmaceutics15041262.

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Nucleic acid vaccines have become a transformative technology to fight emerging infectious diseases and cancer. Delivery of such via the transdermal route could boost their efficacy given the complex immune cell reservoir present in the skin that is capable of engendering robust immune responses. We have generated a novel library of vectors derived from poly(β-amino ester)s (PBAEs) including oligopeptide-termini and a natural ligand, mannose, for targeted transfection of antigen presenting cells (APCs) such as Langerhans cells and macrophages in the dermal milieu. Our results reaffirmed terminal decoration of PBAEs with oligopeptide chains as a powerful tool to induce cell-specific transfection, identifying an outstanding candidate with a ten-fold increased transfection efficiency over commercial controls in vitro. The inclusion of mannose in the PBAE backbone rendered an additive effect and increased transfection levels, achieving superior gene expression in human monocyte-derived dendritic cells and other accessory antigen presenting cells. Moreover, top performing candidates were capable of mediating surface gene transfer when deposited as polyelectrolyte films onto transdermal devices such as microneedles, offering alternatives to conventional hypodermic administration. We predict that the use of highly efficient delivery vectors derived from PBAEs could advance clinical translation of nucleic acid vaccination over protein- and peptide-based strategies.

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Capela, Emanuel V., Maria V. Quental, Pedro Domingues, João A. P. Coutinho, and Mara G. Freire. "Effective separation of aromatic and aliphatic amino acid mixtures using ionic-liquid-based aqueous biphasic systems." Green Chemistry 19, no. 8 (2017): 1850–54. http://dx.doi.org/10.1039/c6gc03060b.

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Ahn, Hee Tae, In Seung Jang, Thinh Viet Dang, Yi Hyang Kim, Dong Hoon Lee, Hyeun Seok Choi, Byung Jo Yu, and Moon Il Kim. "Effective Cryopreservation of a Bioluminescent Auxotrophic Escherichia coli-Based Amino Acid Array to Enable Long-Term Ready-to-Use Applications." Biosensors 11, no. 8 (July 26, 2021): 252. http://dx.doi.org/10.3390/bios11080252.

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Amino acid arrays comprising bioluminescent amino acid auxotrophic Escherichia coli are effective systems to quantitatively determine multiple amino acids. However, there is a need to develop a method for convenient long-term preservation of the array to enable its practical applications. Here, we reported a potential strategy to efficiently maintain cell viability within the portable array. The method involves immobilization of cells within agarose gel supplemented with an appropriate cryoprotectant in individual wells of a 96-well plate, followed by storage under freezing conditions. Six cryoprotectants, namely dimethyl sulfoxide, glycerol, ethylene glycol, polyethylene glycol, sucrose, and trehalose, were tested in the methionine (Met) auxotroph-based array. Carbohydrate-type cryoprotectants (glycerol, sucrose, and trehalose) efficiently preserved the linearity of determination of Met concentration. In particular, the array with 5% trehalose exhibited the best performance. The Met array with 5% trehalose could determine Met concentration with high linearity (R2 value = approximately 0.99) even after storage at −20 °C for up to 3 months. The clinical utilities of the Met and Leu array, preserved at −20 °C for 3 months, were also verified by successfully quantifying Met and Leu in spiked blood serum samples for the diagnosis of the corresponding metabolic diseases. This long-term preservation protocol enables the development of a ready-to-use bioluminescent E. coli-based amino acid array to quantify multiple amino acids and can replace the currently used laborious analytical methods.

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Liu, Xiaomin, Guohui Zhou, Suojiang Zhang, and Guangwen Wu. "Molecular simulation of imidazolium amino acid-based ionic liquids." Molecular Simulation 36, no. 14 (December 2010): 1123–30. http://dx.doi.org/10.1080/08927022.2010.497923.

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Gu, Haiwei, Jin Dai, Fausto Carnevale Neto, Danijel Djukovic, Jiangjiang Zhu, and Daniel Raftery. "Development of a metabolite profile for colorectal cancer detection." Journal of Clinical Oncology 32, no. 3_suppl (January 20, 2014): 422. http://dx.doi.org/10.1200/jco.2014.32.3_suppl.422.

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422 Background: While carcinogenesis of colorectal cancer (CRC) is a complex process involving genetic abnormalities, metabolomics, which aims to establish metabolic responses of living systems to external or internal perturbations, has great potential to develop a metabolite profile specific to CRC for both early detection and treatment monitoring purposes. In this pilot study, we examined the colon cancer-induced alterations of amino acids and their distribution in the three domains of free amino acids (FAAs), free amino acids and soluble peptide amino acids (FAASPAAs), and proteome amino acids (PAAs). Methods: 56 serum samples were collected from 28 colon cancer patients and 28 healthy controls. FAAs were extracted after protein precipitation. FAASPAAs and PAAs were obtained using traditional acid hydrolysis. We utilized LC-MS/MS to make the amino acid measurements, and performed penalized logistic regression analysis on the amino acid signals in the three domains, both individually and in combination. Results: There were 10, 9, and 14 amino acids with low P-values (<0.05) in FAAs, FAASPAAs, and PAAs, respectively, when comparing the two groups. The penalized logistic regression model based on amino acids from the three domains had a sensitivity of 65% when the specificity was 95%. An area under the receiver operator curve (AUROC) of 0.91 was achieved for the combined statistical model. Significant amino acids in statistical modeling included aspartic acid, glutamic acid, glutamine/lysine, and histidine from FAAs, lysine from FAASPAAs, and arginine, serine, and tyrosine from PAAs. Conclusions: To the best of our knowledge, this is the first study to perform a combined analysis of amino acids in the three domains and derive a multivariate statistical model for detecting colon cancer. It was discovered that amino acid concentrations in all three domains are changed significantly in colon cancer and their relative distributions are also altered. The combined analysis helped improve the statistical model for detecting colon cancer. Since this study aims to investigate amino acids that directly connect the metabolome and proteome, it potentially brings new insights to the diagnosis of and mechanism involved in colon cancer development.

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Ravindran, V., and Wayne L. Bryden. "Amino acid availability in poultry—in vitro and in vivo measurements." Australian Journal of Agricultural Research 50, no. 5 (1999): 889. http://dx.doi.org/10.1071/ar98174.

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Methodology to evaluate the protein quality or amino acid availability in feed ingredients for poultry using in vitro (enzymic, chemical, or microbiological assays), indirect in vivo (plasma amino acid assays), or direct in vivo (growth or digestibility assays) measurements has been reviewed. The specific applications and limitations of these methods are examined. In vitro assays are useful in providing information on heat damage in selected protein sources under defined conditions, and on relative ranking of different samples, but they cannot form the basis of practical feed formulations. While growth assays remain the only direct means of confirming nutritional relevance of values obtained by other procedures, in vivo digestibility assays appear to be most useful, at present, to estimate amino acid availability. Amino acid digestibility assays in poultry should be based on the analysis of digesta from the terminal ileum rather than excreta, because of the variable and modifying effects of hindgut microflora. Techniques used to estimate endogenous amino acid losses in poultry are discussed. The needs for correction of endogenous losses in amino acid digestibility calculations and the relative merits of apparent and true digestible amino acid systems are still being debated. It is, however, clear that both digestible amino systems are superior to the total amino acid system currently employed to formulate practical diets. Digestible amino acid values are likely to form the basis of poultry feed formulations in the future. In particular, there is an urgent need for more precise information on the variation in digestible amino acid contents of locally grown ingredients and on the factors causing this variation (e.g. variety, location, season, agronomic practices, processing, etc.).

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A. Nair, Vipin. "2-Iodoxybenzoic Acid: An Oxidant for Functional Group Transformations: (A-Review)." Oriental Journal Of Chemistry 36, no. 05 (October 28, 2020): 792–803. http://dx.doi.org/10.13005/ojc/360501.

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A major application of 2-Iodoxybenzoic acid (IBX) is the oxidation of alcohols to carbonyl compounds, at room temperature. IBX is insoluble in almost all solvents, except DMSO. IBX tolerates amine functionality and is therefore used for the oxidation of amino alcohols to amino carbonyl compounds. IBX oxidizes 1,2-glycols without the cleavage of the glycol carbon-carbon bond. Allylic and benzylic positions are also susceptible to oxidation by IBX. Synthesis of a,b-unsaturated carbonyl compounds from carbonyl compounds can be accomplished by using IBX as oxidant. Silyl enol ethers undergo oxidation upon exposure to IBX and 4-methoxypyridine N-oxide. Water-soluble derivatives of IBX, and polymer-based IBX, with additional advantages, have also been developed. IBX mediated transformations facilitate the construction of diverse heterocyclic systems.

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Gotti, Roberto, Erika Esposito, Diana Luise, Stefano Tullio, Nicolò Interino, Paolo Trevisi, and Jessica Fiori. "Determination of Free Amino Acids in Milk, Colostrum and Plasma of Swine via Liquid Chromatography with Fluorescence and UV Detection." Molecules 27, no. 13 (June 28, 2022): 4153. http://dx.doi.org/10.3390/molecules27134153.

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Amino acids are ubiquitous components of mammalian milk and greatly contribute to its nutritional value. The compositional analysis of free amino acids is poorly reported in the literature even though their determination in the biological fluids of livestock animals is necessary to establish possible nutritional interventions. In the present study, the free amino acid profiles in mature swine milk, colostrum and plasma were assessed using a targeted metabolomics approach. In particular, 20 amino acids were identified and quantified via two alternative and complementary reversed-phase HPLC methods, involving two stationary phases based on core-shell technology, i.e., Kinetex C18 and Kinetex F5, and two detection systems, i.e., a diode array detector (DAD) and a fluorescence detector (FLD). The sample preparation involved a de-proteinization step, followed by pre-chromatographic derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl). The two optimized methods were validated for specificity, linearity, sensitivity, matrix effect, accuracy and precision and the analytical performances were compared. The analytical methods proved to be suitable for free amino acid profiling in different matrices with high sensitivity and specificity. The correlations among amino acid levels in different biological fluids can be useful for the evaluation of physio-pathological status and to monitor the effects of therapeutic or nutritional interventions in humans and animals.

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Wang, Anqi, Yuan Zheng, Wanxin Zhu, Liuxin Yang, Yang Yang, and Jinliang Peng. "Melittin-Based Nano-Delivery Systems for Cancer Therapy." Biomolecules 12, no. 1 (January 12, 2022): 118. http://dx.doi.org/10.3390/biom12010118.

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Melittin (MEL) is a 26-amino acid polypeptide with a variety of pharmacological and toxicological effects, which include strong surface activity on cell lipid membranes, hemolytic activity, and potential anti-tumor properties. However, the clinical application of melittin is restricted due to its severe hemolytic activity. Different nanocarrier systems have been developed to achieve stable loading, side effects shielding, and tumor-targeted delivery, such as liposomes, cationic polymers, lipodisks, etc. In addition, MEL can be modified on nano drugs as a non-selective cytolytic peptide to enhance cellular uptake and endosomal/lysosomal escape. In this review, we discuss recent advances in MEL’s nano-delivery systems and MEL-modified nano drug carriers for cancer therapy.

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Papchenko, Victoriia, Tatiana Matveeva, Sergiy Bochkarev, Anna Belinska, Ekaterina Kunitsia, Anton Chernukha, Oleg Bezuglov, Oleg Bogatov, Dmytro Polkovnychenko, and Sergey Shcherbak. "Development of amino acid balanced food systems based on wheat flour and oilseed meal." Eastern-European Journal of Enterprise Technologies 3, no. 11 (105) (June 30, 2020): 66–76. http://dx.doi.org/10.15587/1729-4061.2020.203664.

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Bao, Yanli, Haiyang Yu, Yu Zhang, and Li Chen. "Comparative study of two poly(amino acid)-based photosensitizer-delivery systems for photodynamic therapy." International Journal of Biological Macromolecules 169 (February 2021): 153–60. http://dx.doi.org/10.1016/j.ijbiomac.2020.12.019.

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40

Souery, Whitney Nicole, Shreedevi Arun Kumar, Daniel Prasca-Chamorro, David Mitchell Moore, Jacob Good, and Corey J. Bishop. "Controlling and quantifying the stability of amino acid-based cargo within polymeric delivery systems." Journal of Controlled Release 300 (April 2019): 102–13. http://dx.doi.org/10.1016/j.jconrel.2019.02.042.

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41

Yu, Kun, Vignesh Peranamallur Rajan, and Ning Dai. "Kinetics and pathways for nitrosamine formation in amino acid-based carbon dioxide capture systems." International Journal of Greenhouse Gas Control 75 (August 2018): 52–62. http://dx.doi.org/10.1016/j.ijggc.2018.04.019.

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Rajendran, Senthilnathan, and Arunachalam Jothi. "An amino acid property-based method for identifying solenoid proteins." International Journal of Data Mining and Bioinformatics 24, no. 3 (2020): 269. http://dx.doi.org/10.1504/ijdmb.2020.112853.

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Jothi, Arunachalam, and Senthilnathan Rajendran. "An amino acid property-based method for identifying solenoid proteins." International Journal of Data Mining and Bioinformatics 24, no. 3 (2020): 269. http://dx.doi.org/10.1504/ijdmb.2020.10033719.

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44

Baxter, Richard. "A Macromolecular approach to peptide-based molecular recognition and catalysis." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1588. http://dx.doi.org/10.1107/s2053273314084113.

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Synthetic peptides incorporating non-natural amino acids provide an opportunity to apply biomimetic principles in the design of both chemical scaffolds and novel pharmaceuticals. Crystallographic analysis can be of significant utility in this area just as elsewhere, but blur the line between small-molecule and macromolecular systems. I will present recent examples combining the tools of macromolecular crystallography techniques with chemical biology to elucidate structures of peptide-based binding and catalytic motifs. First, I will discuss recent structures of a beta-peptide known to spontaneously self-assemble into a octameric bundle wih a defined tertiary-fold. By introducing a non-natural amino acid at the solvent-exposed surface, a binding epitope for poly-alcohols is introduced. [1] Conversely, by modifying the hydrophobic core, the tertiary fold can be re-organized. [2] Second, I will discuss a peptide-based catalyst for the site-specific modification of saccharide units in the scaffold of the antibiotic teicoplanin. [3] While glycosylated small-molecules can be challenging structural-targets, native chemical ligation of the peptide to a macromolecular scaffold allowed for structure determination of the peptide and its binding target. Further structure-based design of more complex non-natural amino acid structures is a promising route to novel peptide-based tools and therapeutics.

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Adhikari, Shiksha, Marijke Schop, Imke J. M. de Boer, and Thom Huppertz. "Protein Quality in Perspective: A Review of Protein Quality Metrics and Their Applications." Nutrients 14, no. 5 (February 23, 2022): 947. http://dx.doi.org/10.3390/nu14050947.

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For design of healthy and sustainable diets and food systems, it is important to consider not only the quantity but also the quality of nutrients. This is particularly important for proteins, given the large variability in amino acid composition and digestibility between dietary proteins. This article reviews measurements and metrics in relation to protein quality, but also their application. Protein quality methods based on concentrations and digestibility of individual amino acids are preferred, because they do not only allow ranking of proteins, but also assessment of complementarity of protein sources, although this should be considered only at a meal level and not a diet level. Measurements based on ileal digestibility are preferred over those on faecal digestibility to overcome the risk of overestimation of protein quality. Integration of protein quality on a dietary level should also be done based on measurements on an individual amino acid basis. Effects of processing, which is applied to all foods, should be considered as it can also affect protein quality through effects on digestibility and amino acid modification. Overall, protein quality data are crucial for integration into healthy and sustainable diets, but care is needed in data selection, interpretation and integration.

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Ludyn, Anatolij, Volodymyr Reutskyy, Viktor Reutskyy, and Yurij Hrynchuk. "Influence of Amino Acids and Alcohols on Catalytic Oxidation of Cyclohexane." Chemistry & Chemical Technology 15, no. 3 (August 15, 2021): 352–58. http://dx.doi.org/10.23939/chcht15.03.352.

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Conducted experiments and collected data show that use of catalytic systems that contain individual amino acids and industrial catalyst – solution of cobalt naphtenate with cyclohexanone – have certain influence on the process of liquid-phase homogeneous oxidation of cyclohexane. The results of spectral studies of binary catalytic systems based on NC using additives of different nature (alcohols and nitrogen-containing modifiers) allow us to propose structural formulas of catalytic complexes.

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Srivastava, Bhartendu K., and Muraleedharan K. Manheri. "Towards a fragment-based approach in gelator design: halogen effects leading to thixotropic, mouldable and self-healing systems in aryl-triazolyl amino acid-based gelators!" Chemical Communications 53, no. 32 (2017): 4485–88. http://dx.doi.org/10.1039/c7cc00980a.

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Abu Ali, Ola A., Hosam A. Saad, and Bodor M. A. Al Malki. "Synthesis of Some New Folic Acid-Based Heterocycles of Anticipated Biological Activity." Molecules 26, no. 2 (January 12, 2021): 368. http://dx.doi.org/10.3390/molecules26020368.

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To date, no fused heterocycles have been formed on folic acid molecules; for this reason, and others, our target is to synthesize new derivatives of folic acid as isolated or fused systems. Folic acid 1 reacted with ethyl pyruvate, triethyl orthoformate, ethyl chloroformate, thioformic acid hydrazide, and aldehydes to give new derivatives of folic acid 2–6a,b. Moreover, It reacted with benzylidene malononitrile, acetylacetone, ninhydrin, ethyl acetoacetate, ethyl cyanoacetate, and ethyl chloroacetate to give the pteridine fused systems 10–15, respectively. Ethoxycarbonylamino derivate 5 reacted with some nucleophiles containing the NH2 group, such as aminoguanidinium hydrocarbonate, hydrazine hydrate, glycine, thioformic acid hydrazide, and sulfa drugs in different conditions to give the urea derivatives 16–20a,b. Compound 4 reacted with the same nucleophiles to give the methylidene amino derivatives 21–24a,b. The fused compound 10 reacted with thioglycolic acid carbon disulfide, malononitrile, and formamide to give the four cyclic fused systems 25–30, respectively. The biological activity of some synthesized showed moderate effect against bacteria, but no effect shown towards fungi.

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Koo, Sangmo. "Flexible Heater Fabrication Using Amino Acid-Based Ink and Laser-Direct Writing." Micromachines 13, no. 12 (December 13, 2022): 2209. http://dx.doi.org/10.3390/mi13122209.

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Nature’s systems have evolved over a long period to operate efficiently, and this provides hints for metal nanoparticle synthesis, including the enhancement, efficient generation, and transport of electrons toward metal ions for nanoparticle synthesis. The organic material-based ink composed of the natural materials used in this study requires low laser power for sintering compared to conventional nanoparticle ink sintering. This suggests applicability in various and sophisticated pattern fabrication applications without incurring substrate damage. An efficient electron transfer mechanism between amino acids (e.g., tryptophan) enables silver patterning on flexible polymer substrates (e.g., PET) by laser-direct writing. The reduction of silver ions to nanoparticles was induced and sintered by simultaneous photo/thermalchemical reactions on substrates. Furthermore, it was possible to fabricate a stable, transparent, and flexible heater that operates under mechanical deformation.

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Jones, Eugenia M. C. "Na+ - and Cl−-dependent neurotransmitter transporters in bovine retina: Identification and localization by in situ hybridization histochemistry." Visual Neuroscience 12, no. 6 (November 1995): 1135–42. http://dx.doi.org/10.1017/s0952523800006775.

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AbstractThe physiological actions of biogenic amine and amino-acid neurotransmitters are terminated by their removal from the synaptic cleft by specific high-affinity transport proteins. The members of the Na+- and Cl−-dependent neurotransmitter transporter family expressed in bovine retina and responsible for the uptake of biogenic amine and amino-acid neurotransmitters were identified using a reverse transcriptase-polymerase chain reaction-based approach. cDNA clones encoding bovine homologues of glycine (GLYT-1), γ-aminobutyric acid (GAT-1) creatine (CreaT), and orphan (NTT4) transporters were identified using this strategy. The expression pattern of mRNAs encoding these proteins in the retina was determined by in situ hybridization histochemistry GLYT-1 CreaT NTT4 and GAT-1 mRNAs were expressed in the retina by cells in the inner nuclear inner plex, iform and ganglion cell layers They were not expressed at detectable levels in the photoreceptor cells whose cell bodies are in the outer nuclear layer and are the most abundant cell type in the retina GLYT-1 mRNA was present exclusively in the proximal inner nuclear layer GAT-1 mRNA was localized to both the inner nuclear and ganglion cell layers CreaT mRNA was expressed in all cell types in the retina except photoreceptors and NTT4 mRNA was expressed by a sub subpoulation of cells in the ganglion cell laver. Elucidation of the expression pattern of these neurotransmitter transporter mRNAs in the retina provides a basis for studies of the role of glycine γ-aminobutyric acid and creatine transporters in retinal function.

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Journal articles on the topic 'Amino acid- based systems'

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