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Amino Acids

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https://www.readbyqxmd.com/read/30327888/novel-efficient-facile-and-comprehensive-protocol-for-post-column-amino-acid-analysis-of-icatibant-acetate-containing-natural-and-unnatural-amino-acids-using-the-qbd-approach
#1
Yagnakirankumar Komaravolu, Venugopala Rao Dama, Thirumala Chary Maringanti
Qualitative and quantitative determination of amino acid composition using amino acid analysis (AAA) is an important quality attribute and considered an identity of therapeutic peptide drugs by the regulatory agencies. Although huge literature is available on pre- and post- column derivatization AAA methods, arriving at an appropriate hydrolysis protocol coupled with adequate separation of the derivatized/underivatized amino acids is always challenging. Towards achieving a facile and comprehensive protocol for AAA, the present work is geared towards developing a deeper understanding of the extent of hydrolysis of peptide, and the nature and stability of amino acids present in the peptide backbone...
October 16, 2018: Amino Acids
https://www.readbyqxmd.com/read/30311082/the-self-disproportionation-of-enantiomers-sde-of-%C3%AE-amino-acid-derivatives-facets-of-steric-and-electronic-properties
#2
Takuma Hosaka, Tomomi Imai, Alicja Wzorek, Magdalena Marcinkowska, Anna Kolbus, Osamu Kitagawa, Vadim A Soloshonok, Karel D Klika
α-Amino acids (α-AAs) are in extremely high demand in nearly every sector of the food and health-related chemical industries and continue to be the subject of intense multidisciplinary research. The self-disproportionation of enantiomers (SDE) is an emerging and one of the least studied areas of α-AA or enantiomeric properties, critically important for their production and application. In the present work, we report a detailed study of the SDE via achiral, gravity-driven column chromatography for a set of N-acylated, N-carbonylated, N-fluoroacylated, and N-thioacylated α-amino acid esters...
October 11, 2018: Amino Acids
https://www.readbyqxmd.com/read/30302566/development-and-validation-of-a-sensitive-lc-ms-ms-assay-for-the-quantification-of-anserine-in-human-plasma-and-urine-and-its-application-to-pharmacokinetic-study
#3
Inge Everaert, Giovanna Baron, Silvia Barbaresi, Ettore Gilardoni, Crescenzo Coppa, Marina Carini, Giulio Vistoli, Tine Bex, Jan Stautemas, Laura Blancquaert, Wim Derave, Giancarlo Aldini, Luca Regazzoni
Carnosine (beta-alanyl-L-histidine) and its methylated analogue anserine are present in relevant concentrations in the omnivore human diet. Several studies reported promising therapeutic potential for carnosine in various rodent models of oxidative stress and inflammation-related chronic diseases. Nevertheless, the poor serum stability of carnosine in humans makes the translation of rodent models hard. Even though anserine and carnosine have similar biochemical properties, anserine has better serum stability...
October 9, 2018: Amino Acids
https://www.readbyqxmd.com/read/30298243/fragments-of-the-second-transmembrane-helix-of-three-g-protein-coupled-receptors-comparative-synthetic-structural-and-conformational-studies
#4
Douglas D Lopes, Jamille H Cuvero, Mariana M L Ferreira, Rogério L Silva, Sinval E G Souza, Luciana Malavolta, Shirley Schreier, Clovis R Nakaie
We compared the synthesis and structural/conformational details of the (66-97) segments of the second transmembrane helix of AT1, MAS and B2, all of which belong to the class of G-protein-coupled receptors (GPCR). Step-by-step monitoring of the coupling reactions during the growth of these transmembrane peptides revealed that the increase in the level of difficulty started at the 6-10 regions of the sequence. Possibly due to their long and hydrophobic sequences, the final estimated synthesis yields decreased progressively by up to 20-25%...
October 8, 2018: Amino Acids
https://www.readbyqxmd.com/read/30288604/ensembling-three-multicomponent-reactions-for-the-synthesis-of-a-novel-category-of-pseudo-peptides-containing-dithiocarbamate-and-n-x-heterocylic-groups
#5
Maryam Khalesi, Azim Ziyaei Halimehjani, Max Franz, Marc Schmidtmann, Jürgen Martens
Consecutive multicomponent reactions have been applied for the synthesis of novel pseudo-peptides bearing dithiocarbamate and N,X-heterocyclic groups (X = S, O) in only one structure. The first multicomponent reaction includes the synthesis of dithiocarbamates using an amine or amino acid, CS2 and an electrophile. The second MCR is synthesis of Asinger imines using 2-chloroisobutyraldehyde, NaXH (X = S, O), ketone and ammonia. The final MCR is Ugi reaction to afford the corresponding three-dimensional pseudo-peptides...
October 4, 2018: Amino Acids
https://www.readbyqxmd.com/read/30288603/a-conformationally-restricted-gaba-analogue-based-on-octahydro-1h-cyclopenta-b-pyridine-scaffold
#6
Kostiantyn P Melnykov, Dmitriy M Volochnyuk, Sergey V Ryabukhin, Eduard B Rusanov, Oleksandr O Grygorenko
An approach to rel-(4aS,6R,7aR)-octahydro-1H-cyclopenta[b]pyridine-6-carboxylic acid-a bicyclic conformationally restricted γ-aminobutyric acid (GABA) analogue was developed. The eight-step sequence relied on the reaction of 2,3-bis(chloromethyl)pyridine and a C1 -binucleophile and the catalytic reduction of the pyridine ring as the key steps and allowed for the preparation of the title compound in 9.0% overall yield. Assessment of the octahydro-1H-cyclopenta[b]pyridine scaffold geometry showed that this template can be considered truly three-dimensional...
October 4, 2018: Amino Acids
https://www.readbyqxmd.com/read/30267164/studies-on-acid-stability-and-solid-phase-block-synthesis-of-peptide-peptoid-hybrids-ligands-for-formyl-peptide-receptors
#7
Anna Mette Hansen, Sarah Line Skovbakke, Simon Bendt Christensen, Iris Perez-Gassol, Henrik Franzyk
α-Peptoids as well as peptide/α-peptoid hybrids and peptide/β-peptoid hybrids constitute major classes of proteolytically stable peptidomimetics that have been extensively investigated as mimetics of biologically active peptides. Representatives of lipidated peptide/β-peptoid hybrids have been identified as promising immunomodulatory lead compounds, and hence access to these via protocols suitable for gram-scale synthesis is warranted to enable animal in vivo studies. Recent observations indicated that several byproducts appear in crude mixtures of relatively short benzyl-based peptide/β-peptoid oligomers, and that these were most predominant when the β-peptoid units displayed an α-chiral benzyl side chain...
September 28, 2018: Amino Acids
https://www.readbyqxmd.com/read/30264172/synthesis-18-f-labelling-and-radiopharmacological-characterisation-of-the-c-terminal-30mer-of-clostridium-perfringens-enterotoxin-as-a-potential-claudin-targeting-peptide
#8
Reik Löser, Miriam Bader, Manuela Kuchar, Robert Wodtke, Jens Lenk, Johanna Wodtke, Konstantin Kuhne, Ralf Bergmann, Cathleen Haase-Kohn, Marie Urbanová, Jörg Steinbach, Jens Pietzsch
The cell surface receptor claudin-4 (Cld-4) is upregulated in various tumours and represents an important emerging target for both diagnosis and treatment of solid tumours of epithelial origin. The C-terminal fragment of the Clostridium perfringens enterotoxin cCPE290-319 appears as a suitable ligand for targeting Cld-4. The synthesis of this 30mer peptide was attempted via several approaches, which has revealed sequential SPPS using three pseudoproline dipeptide building blocks to be the most efficient one...
September 27, 2018: Amino Acids
https://www.readbyqxmd.com/read/30264171/does-l-leucine-supplementation-cause-any-effect-on-glucose-homeostasis-in-rodent-models-of-glucose-intolerance-a-systematic-review
#9
REVIEW
Henver S Brunetta, Carolina Q de Camargo, Everson A Nunes
L-Leucine has been used to improve metabolic outcomes in glucose-intolerant rodent models. However, because studies have used different experimental models and conditions it is difficult to establish the best approach for new clinical trials evaluating the potential effects of L-leucine on glucose homeostasis. We performed a systematic review to report the effect of L-leucine supplementation on glucose homeostasis in rodents with glucose intolerance. The search engines MEDLINE and ScienceDirect were applied using MeSH terms...
September 27, 2018: Amino Acids
https://www.readbyqxmd.com/read/30264170/rehydration-during-exercise-prevents-the-increase-of-homocysteine-concentrations
#10
Beatriz Maroto-Sánchez, Olga Lopez-Torres, Jara Valtueña, Pedro J Benito, Gonzalo Palacios, Ángel Enrique Díaz-Martínez, Domingo González-Lamuño, Angelo Zinellu, Marcela González-Gross, Ciriaco Carru
This study aimed to assess the effect of rehydration during and after acute aerobic submaximal exercise on total homocysteine (tHcy) concentrations and related parameters in physically active adult males. Twenty trained males (29.4 ± 7.9 years old) completed four exercise tests: two without rehydration during exercise (NH1 and NH2), one with rehydration during exercise using water (H1) and one with rehydration during exercise using an isotonic sports drink (H2). After finishing the exercise tests, subjects followed a rehydration protocol for 2 h...
September 27, 2018: Amino Acids
https://www.readbyqxmd.com/read/30255260/anti-obesity-effect-of-taurine-through-inhibition-of-adipogenesis-in-white-fat-tissue-but-not-in-brown-fat-tissue-in-a-high-fat-diet-induced-obese-mouse-model
#11
Kyoung Soo Kim, Min Ju Jang, Sungsoon Fang, Seul Gi Yoon, Il Yong Kim, Je Kyung Seong, Hyung-In Yang, Dae Hyun Hahm
This study was conducted to evaluate the anti-obesity effects of long-term taurine supplementation in a mild obese ICR mouse model and to study the mechanism by which taurine induces weight loss. Three groups of male ICR mice were fed a normal chow diet, a high-fat diet (HFD), or an HFD supplemented with 2% taurine in drinking water for 28 weeks. Body weight was measured every week. Metabolic, behavioral, and physiological monitoring were carried out using PhenoMaster at 28 weeks. Interscapular brown fat (BAT), inguinal white fat tissue (WAT), and quadriceps muscle were analyzed and compared to assess the change of gene expression related to adipogenesis...
September 25, 2018: Amino Acids
https://www.readbyqxmd.com/read/30238253/regulation-of-carbamoylphosphate-synthesis-in-escherichia-coli-an-amazing-metabolite-at-the-crossroad-of-arginine-and-pyrimidine-biosynthesis
#12
REVIEW
Daniel Charlier, Phu Nguyen Le Minh, Martine Roovers
In all organisms, carbamoylphosphate (CP) is a precursor common to the synthesis of arginine and pyrimidines. In Escherichia coli and most other Gram-negative bacteria, CP is produced by a single enzyme, carbamoylphosphate synthase (CPSase), encoded by the carAB operon. This particular situation poses a question of basic physiological interest: what are the metabolic controls coordinating the synthesis and distribution of this high-energy substance in view of the needs of both pathways? The study of the mechanisms has revealed unexpected moonlighting gene regulatory activities of enzymes and functional links between mechanisms as diverse as gene regulation and site-specific DNA recombination...
September 20, 2018: Amino Acids
https://www.readbyqxmd.com/read/30232574/pgc1%C3%AE-regulates-acmsd-expression-through-cooperation-with-hnf4%C3%AE
#13
Manami Koshiguchi, Shizuka Hirai, Yukari Egashira
ACMSD is a tryptophan metabolic key enzyme. HNF4α regulates the transcription of some energy-metabolic enzymes by cooperating with PGC1α, a major transcriptional co-regulator involved in energy metabolism. In this study, we investigated the involvement of PGC1α in Acmsd expression through cooperation with HNF4α. Luciferase reporter assay was performed in NIH3T3 cells using a reporter vector containing HNF4α responsive elements in the Acmsd 5' upstream transcriptional regulatory region together with HNF4α and/or PGC1α expression vectors...
September 19, 2018: Amino Acids
https://www.readbyqxmd.com/read/30225664/taurine-exhibits-an-apoptosis-inducing-effect-on-human-nasopharyngeal-carcinoma-cells-through-pten-akt-pathways-in-vitro
#14
Feng He, Ning Ma, Kaoru Midorikawa, Yusuke Hiraku, Shinji Oikawa, Zhe Zhang, Guangwu Huang, Kazuhiko Takeuchi, Mariko Murata
Nasopharyngeal carcinoma (NPC) is a distinctive type of head and neck malignancy with a high incidence in southern China. Previous studies have confirmed that taurine shows an anti-cancer effect on a variety of human tumors by inhibiting cell proliferation and inducing apoptosis. However, the underlying molecular mechanism of its anti-cancer effect on NPC is not well understood. To clarify these anti-cancer mechanisms, we performed cell viability and colony formation assays. Apoptotic cells were quantified by flow cytometry...
September 17, 2018: Amino Acids
https://www.readbyqxmd.com/read/30225663/-1-h-nmr-spectroscopy-in-the-presence-of-mosher-acid-to-rapidly-determine-the-enantiomeric-composition-of-amino-acid-benzyl-esters-chirons-susceptible-to-easy-racemization
#15
Cristiano Bolchi, Gabriella Roda, Marco Pallavicini
Amino acid benzyl esters are very useful chiral synthons, whose enantiomeric purity needs to be carefully verified because of their susceptibility to easy racemization. Alternative to chiral HPLC, 1 H NMR in the presence of a chiral solvating agent (CSA) can allow a more rapid and acceptably accurate determination of the enantiomeric composition, if explicit spectral non-equivalence of one or more protons of the analyte enantiomers is found. Here, we have studied the enantiodiscrimination of 13 amino acid benzyl esters by 1 H NMR in the presence of (R)-Mosher acid and in different solvents proving that, for 5 of them (Ala, Pro, Glu, Met, Ser), efficient enantiodifferentiation can be achieved and ≤ 98% enatiomeric excesses accurately determined...
September 17, 2018: Amino Acids
https://www.readbyqxmd.com/read/30209603/a-kinetic-model-of-carnosine-synthesis-in-human-skeletal-muscle
#16
Dmitry Spelnikov, Roger Charles Harris
Drawing on previously published data, a mathematical model is proposed to describe the synthesis of carnosine in muscle using a slow release β-alanine supplement (SR-CarnoSyn® ). The model pre-supposes that the rate of synthesis for any given dose of β-alanine (within the range 1.6-6.4 g day-1 ) is constant with time, but is first order with respect to daily β-alanine dose. Simultaneously with synthesis, decay in carnosine is also assumed to be occurring, the rate in this case being a function of the concentration of carnosine...
September 12, 2018: Amino Acids
https://www.readbyqxmd.com/read/30206707/regulation-of-glucose-and-lipid-metabolism-by-the-pancreatic-and-extra-pancreatic-actions-of-taurine
#17
REVIEW
Rosane A Ribeiro, Maria L Bonfleur, Thiago M Batista, Patricia C Borck, Everardo M Carneiro
The beneficial actions of L-taurine (Tau) against glucose intolerance, obesity, type 2 diabetes (T2D), and non-alcoholic fat liver disease (NAFLD) have been linked to its antioxidant and anti-inflammatory effects, which ameliorate tissue insulin sensitivity. Importantly, there are several lines of evidence that indicate a direct action of Tau on the endocrine pancreas to regulate the secretion and paracrine actions of insulin, glucagon, and somatostatin. Furthermore, Tau can also ameliorate glucose metabolism through the enhancement of insulin signaling...
September 11, 2018: Amino Acids
https://www.readbyqxmd.com/read/30203393/simplified-plasma-essential-amino-acid-based-profiling-provides-metabolic-information-and-prognostic-value-additive-to-traditional-risk-factors-in-heart-failure
#18
Chao-Hung Wang, Mei-Ling Cheng, Min-Hui Liu
In heart failure (HF), metabolic disturbances represent functional perturbations in peripheral tissues and also predict patient outcomes. This study developed a simplified essential amino acid-based profile and tested whether it could improve prognostication. Plasma essential amino acids and lipidomics were measured on 1084 participants. The initial cohort included 94 normal controls and 599 patients hospitalized due to acute/decompensated HF. The validation cohort included 391 HF patients. Patients were followed for composite events (death/HF related re-hospitalization) and were categorized into three groups: high risk type 1 (leucine ≥145 μM and phenylalanine ≥ 88...
September 10, 2018: Amino Acids
https://www.readbyqxmd.com/read/30196335/mitochondrial-targeting-domain-of-noxa-causes-necrosis-in-apoptosis-resistant-tumor-cells
#19
Dai-Trang Nguyen, Siyuan He, Ji-Hye Han, Junghee Park, Young-Woo Seo, Tae-Hyoung Kim
The resistance of tumor cells to apoptosis-inducing anticancer agents is regarded as a major impediment for the treatment of cancer patients. This study aimed to examine the possibility whether a necrosis-inducing peptide containing the mitochondria-targeting domain (MTD) of NOXA kills tumor cells that are resistant to apoptosis-inducing anticancer agents. To examine this possibility, we established doxorubicin-resistant (Dox-Res) cells by treating CT26 cells with increasing amounts of doxorubicin. The apoptosis resistance of the Dox-Res CT26 cells was confirmed by measuring the cell viability and activation of caspases...
September 8, 2018: Amino Acids
https://www.readbyqxmd.com/read/30191331/dietary-l-lysine-supplementation-altered-the-content-of-pancreatic-polypeptide-enzymes-involved-in-glutamine-metabolism-and-%C3%AE-actin-in-rats
#20
Chao-Wu Xiao, Caroline Faddoul, Carla Wood
This study investigated the effects of Lys supplementation on serum pancreatic polypeptide (PP), glutamine (Gln) levels and the expression of PP, Gln synthetase (GlnS), glutaminase (Gls) and β-actin in different tissues such as pancreas, skeletal muscle, liver and kidney in rats. Male Sprague-Dawley rats were fed diets containing 7% casein supplemented with either 0% (Control), 1%, 1.5%, 3% Lys or 3% Lys with 1.5% Arg for a week. All rats were necropsied for collection of blood and tissues. Expression of PP, GlnS, Gls, and β-actin in tissues were determined using Western blotting...
September 6, 2018: Amino Acids
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