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"Amino acid"

Yushuang Chen, Shunxi Dong, Xi Xu, Xiaohua Liu, Xiaoming Feng
The first example of catalytic insertion/asymmetric Claisen rearrangement tandem reaction of N-sulfonyl-1,2,3-triazoles with allyl alcohol esters was achieved by bimetallic relay catalytic systems involving achiral rhodium salt and chiral N,N'-dioxide-indium(III) complex. This manifold could overcome the limitation of single RhII catalysis, providing a straight and facile route to various enantioenriched β/γ-amino acid derivatives in high yields (up to 99%) with excellent diastereo- and enantioselectivities (up to > 95:5 dr, 98:2 er)...
October 20, 2018: Angewandte Chemie
Loukas I Goulatis, Rasika Ramanathan, Eric V Shusta
Expressing antibodies as fusions to the non-self cleaving Mxe GyrA intein allows for site-specific chemical functionalization via expressed protein ligation. It is highly desirable to maximize the yield of functionalizable protein; and previously an evolved intein, 202-08, was identified that could increase protein fusion production in yeast. Given that the -1 amino acid residue upstream of inteins can affect cleavage efficiency, we examined the effects of amino acid variability at this position on 202-08 intein cleavage efficiency and secretion yield...
October 20, 2018: Biotechnology Progress
Wanderson M Silva, Cassiana S Sousa, Leticia C Oliveira, Siomar C Soares, Gustavo F M H Souza, Guilherme C Tavares, Cristiana P Resende, Edson L Folador, Felipe L Pereira, Henrique Figueiredo, Vasco Azevedo
Lactococcus lactis is a bacteria with high biotechnological potential, where is frequently used in the amino acid production and production of fermented dairy products, as well as drug delivery systems and mucosal vaccine vector. The knowledge of a functional core proteome is important extremely for both fundamental understanding of cell functions and for synthetic biology applications. In this study, we characterized the L. lacits proteome from proteomic analysis of four biotechnological strains L. lactis: L...
October 19, 2018: Microbial Biotechnology
Viktor Kožich, Tamás Ditrói, Jitka Sokolová, Michaela Křížková, Jakub Krijt, Pavel Ješina, Peter Nagy
BACKGROUND AND PURPOSE: Homocystinurias are rare genetic defects characterized by altered fluxes of sulfur compounds including homocysteine and cysteine. We explored whether the severely perturbed sulfur amino acid metabolism in patients with homocystinurias affects metabolism of hydrogen sulfide. EXPERIMENTAL APPROACH: We studied ten treated patients with a block in conversion of homocysteine to cysteine due to CBS deficiency (CBSD), and in six treated patients with remethylation defects (RMD) and enhanced flux of sulfur metabolites via transsulfuration...
October 19, 2018: British Journal of Pharmacology
Yanyan Xia, Yuanying Zhang, Mengjiao Shen, Hongpan Xu, Zhiyang Li, Nongyue He
Golgi protein 73 (GP73, also referred to as Golph 2) with 400 amino acids is a 73 kDa transmembrane glycoprotein typically found in the cis-Golg complex. It is primarily expressed in epithelial cells, which has been found upregulated in hepatocytes in patients suffering from both viral and non-viral liver diseases. GP73 has drawn increasing attention for its potential application in the diagnosis of liver diseases such as hepatitis, liver cirrhosis and liver cancer. Herein, we reviewed the discovery history of GP73 and summarized studies by many groups around the world, aiming at understanding its structure, expression, function, detection methods and the relationship between GP73 and liver diseases in various settings...
October 19, 2018: Cell Proliferation
Hari Leontiadou, Ioannis Galdadas, Christina Athanasiou, Zoe Cournia
Phosphoinositide 3-kinase alpha (PI3Kα) is involved in fundamental cellular processes including cell proliferation and differentiation and is frequently mutated in human malignancies. One of the most common mutations is E545K, which results in an amino acid substitution of opposite charge. It has been recently proposed that in this oncogenic charge-reversal mutation, the interactions between the protein catalytic and regulatory subunits are abrogated, resulting in loss of regulation and constitutive PI3Kα activity, which can lead to oncogenesis...
October 19, 2018: Scientific Reports
Mohd Faheem Khan, Sanjukta Patra
Protein stability is affected at different hierarchies - gene, RNA, amino acid sequence and structure. Gene is the first level which contributes via varying codon compositions. Codon selectivity of an organism differs with normal and extremophilic milieu. The present work attempts at detailing the codon usage pattern of six extremophilic classes and their harmony. Homologous gene datasets of thermophile-mesophile, psychrophile-mesophile, thermophile-psychrophile, acidophile-alkaliphile, halophile-nonhalophile and barophile-nonbarophile were analysed for filtering statistically significant attributes...
October 19, 2018: Scientific Reports
Ilya D Solovyev, Alexandra V Gavshina, Aditya S Katti, Alexey I Chizhik, Leonid M Vinokurov, Grigory D Lapshin, Tatiana V Ivashina, Maria G Khrenova, Igor I Kireev, Ingo Gregor, Jörg Enderlein, Alexander P Savitsky
Photoconvertible fluorescent proteins (PCFPs) are widely used as markers for the visualization of intracellular processes and for sub-diffraction single-molecule localization microscopy. Although wild type of a new photoconvertible fluorescent protein SAASoti tends to aggregate, we succeeded, via rational mutagenesis, to obtain variants that formed either tetramers or monomers. We compare two approaches: one is based on the structural similarity between SAASoti and Kaede, which helped us to identify a single point mutation (V127T) at the protein's hydrophobic interface that leads to monomerization...
October 19, 2018: Scientific Reports
Ngan N T Nguyen, Yun-Sook Lim, Lap P Nguyen, Si C Tran, Trang T D Luong, Tram T T Nguyen, Hang T Pham, Han N Mai, Jae-Woong Choi, Sang-Seop Han, Soon B Hwang
Hepatitis C virus (HCV) exploits an extensive network of host proteins to maintain chronic infection. Using RNA-Seq technology, we identified 30 host genes that were differentially expressed in cell culture grown HCV (HCVcc)-infected cells. Of these candidate genes, we selected solute carrier family 3 member 2 (SLC3A2) for further investigation. SLC3A2, also known as CD98hc, is a member of the solute carrier family and encodes a subunit of heterodimeric amino acid transporter. SLC3A2 and LAT1 constitute a heterodimeric transmembrane protein complex that catalyzes amino acid transport...
October 19, 2018: Scientific Reports
Carolin Hacker, Xiaofeng Cai, Carsten Kegler, Lei Zhao, A Katharina Weickhmann, Jan Philip Wurm, Helge B Bode, Jens Wöhnert
Several peptides in clinical use are derived from non-ribosomal peptide synthetases (NRPS). In these systems multiple NRPS subunits interact with each other in a specific linear order mediated by specific docking domains (DDs), whose structures are not known yet, to synthesize well-defined peptide products. In contrast to classical NRPSs, single-module NRPS subunits responsible for the generation of rhabdopeptide/xenortide-like peptides (RXPs) can act in different order depending on subunit stoichiometry thereby producing peptide libraries...
October 19, 2018: Nature Communications
Rituraj Pal, Michela Palmieri, Arindam Chaudhury, Tiemo Jürgen Klisch, Alberto di Ronza, Joel R Neilson, George G Rodney, Marco Sardiello
The mechanistic target of rapamycin complex 1 (mTORC1) regulates cell survival and autophagy, and its activity is regulated by amino acid availability. Rag GTPase-GATOR1 interactions inhibit mTORC1 in the absence of amino acids, and GATOR1 release and activation of RagA/B promotes mTORC1 activity in the presence of amino acids. However, the factors that play a role in Rag-GATOR1 interaction are still poorly characterized. Here, we show that the tyrosine kinase Src is crucial for amino acid-mediated activation of mTORC1...
October 19, 2018: Nature Communications
Devesh Bhimsaria, José A Rodríguez-Martínez, Junkun Pan, Daniel Roston, Elif Nihal Korkmaz, Qiang Cui, Parameswaran Ramanathan, Aseem Z Ansari
We have developed Differential Specificity and Energy Landscape (DiSEL) analysis to comprehensively compare DNA-protein interactomes (DPIs) obtained by high-throughput experimental platforms and cutting edge computational methods. While high-affinity DNA binding sites are identified by most methods, DiSEL uncovered nuanced sequence preferences displayed by homologous transcription factors. Pairwise analysis of 726 DPIs uncovered homolog-specific differences at moderate- to low-affinity binding sites (submaximal sites)...
October 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
Marcelo E Guerin, Guillaume Stirnemann, David Giganti
An immense repertoire of protein chemical modifications catalyzed by enzymes is available as proteomics data. Quantifying the impact of the conformational dynamics of the modified peptide remains challenging to understand the decisive kinetics and amino acid sequence specificity of these enzymatic reactions in vivo, because the target peptide must be disordered to accommodate the specific enzyme-binding site. Here, we were able to control the conformation of a single-molecule peptide chain by applying mechanical force to activate and monitor its specific cleavage by a model protease...
October 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
Le Xu, Venkat R Chirasani, Jordan S Carter, Daniel A Pasek, Nikolay V Dokholyan, Naohiro Yamaguchi, Gerhard Meissner
Cryo-electron micrograph studies recently have identified a Ca2+-binding site in the 2,200-kDa ryanodine receptor ion channel (RyR1) in skeletal muscle.[MS2]  To clarify the role of this site in regulating RyR1 activity, here we applied mutational, electrophysiological, and computational methods. Three amino acid residues that interact directly with Ca2+ were replaced, and these RyR1 variants were expressed in HEK293 cells. Single-site RyR1-E3893Q, E3893V, E3967Q, E3967V, and T5001A variants and double-site RyR1-E3893Q/E3967Q and E3893V/E3967V variants displayed cellular Ca2+ release in response to caffeine, which indicated that they retained functionality as caffeine-sensitive, Ca2+-conducting channels in the HEK293 cell system...
October 19, 2018: Journal of Biological Chemistry
Jonathan Dorival, Sophie Ruppert, Melissa Gunnoo, Adam Orłowski, Maylis Chapelais-Baron, Jérôme Dabin, Aurore Labourel, Damien Thompson, Gurvan Michel, Mirjam Czjzek, Sabine Genicot
Cell walls of marine macroalgae are composed of diverse polysaccharides that provide abundant carbon sources for marine heterotrophic bacteria. Among them, Zobellia galactanivorans is considered as a model for studying algae-bacteria interactions. The degradation of typical algal polysaccharides, such as agars or alginate, has been intensively studied in this bacterium, but the catabolism of plant-like polysaccharides is essentially uncharacterized. Here we identify a polysaccharide utilization locus in the genome of Z...
October 19, 2018: Biochemical Journal
Mingming Qin, Haigang Song, Xin Dai, Yaozong Chen, Zhihong Guo
The bacterial enzyme MenD, or 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate (SEPHCHC) synthase, catalyzes an essential Stetter reaction in menaquinone (vitamin K2) biosynthesis via thiamine diphosphate (ThDP)-bound tetrahedral post-decarboxylation intermediates. The detailed mechanism of this intermediate chemistry, however, is still poorly understood, but of significant interest given that menaquinone is an essential electron transporter in many pathogenic bacteria. Here, we used site-directed mutagenesis, enzyme kinetic assays, and protein crystallography to reveal an active-inactive intermediate equilibrium in MenD catalysis and its modulation by two conserved active-site arginine residues...
October 19, 2018: Biochemical Journal
Stefano Murtas, Roberto Aquilani, Maria Luisa Deiana, Paolo Iadarola, Romina Secci, Mariella Cadeddu, Stefano Salis, Doriana Serpi, Piergiorgio Bolasco
OBJECTIVE: The objective of the study was to quantify the loss of total amino acids (TAAs), nonessential amino acids, essential amino acids, and branched chain amino acids (BCAAs) produced by high-efficiency hemodialysis (HEHD), postdilution hemodiafiltration (HDFpost), and predilution hemodiafiltration (HDFpre) using high ultrafiltration volumes; and to define the specific AA losses registered in HEHD, HDFpost, and HDFpre; to identify a potential metabolic and nutritional decline into protein energy wasting; to compare AA analysis of arterial blood samples taken from healthy controls and patients with end-stage renal disease undergoing hemodialysis...
October 16, 2018: Journal of Renal Nutrition
Dorna Davani-Davari, Iman Karimzadeh, Mohammad Mahdi Sagheb, Hossein Khalili
One of the major concerns about taking amino acid supplements is their potential adverse effects on the kidney as a major organ involved in the metabolism and excretion of exogenous substances. The aim of this study is to review available data about renal safety of the most prominent amino acid supplements including L-arginine, glutamine and also L-carnitine as well as creatine (as amino acid derivatives) in athletes and bodybuilders. The literature was searched by keywords such as "L-carnitine", "L-arginine", "glutamine", and "kidney injury" in databases such as Scopus, Medline, Embase, and ISI Web of Knowledge...
October 16, 2018: Journal of Renal Nutrition
Shirley Kartaram, Marco Mensink, Marc Teunis, Eric Schoen, Gerrit Witte, Lonneke Janssen Duijghuijsen, Martie Verschuren, Karin Mohrmann, Laura M'Rabet, Karen Knipping, Harriet Wittink, Ardy van Helvoort, Johan Garssen, Renger Witkamp, Raymond Pieters, Klaske van Norren
BACKGROUND & AIMS: Plasma citrulline concentration is considered to be a marker for enterocyte metabolic mass and to reflect its reduction as may occur during intestinal dysfunction. Strenuous exercise can act as a stressor to induce small intestinal injury. Our previous studies suggest that this comprises the intestinal ability to produce citrulline from a glutamine-rich protein bolus. In this study we investigated the effects of different exercise intensities and hydration state on citrulline and iFABP levels following a post-exercise glutamine bolus in healthy young men...
September 28, 2018: Clinical Nutrition: Official Journal of the European Society of Parenteral and Enteral Nutrition
Jeroen van Bergenhenegouwen, Saskia Braber, Reinilde Loonstra, Nicole Buurman, Lieke Rutten, Karen Knipping, Paul J Savelkoul, Lucien F Harthoorn, Frode L Jahnsen, Johan Garssen, Anita Hartog
The conditionally essential amino acid glycine functions as inhibitory neurotransmitter in the mammalian central nervous system. Moreover, it has been shown to act as an anti-inflammatory compound in animal models of ischemic perfusion, post-operative inflammation, periodontal disease, arthritis and obesity. Glycine acts by binding to a glycine-gated chloride channel, which has been demonstrated on neurons and immune cells, including macrophages, polymorphonuclear neutrophils and lymphocytes. The present study aims to evaluate the effect of glycine on allergy development in a cow's milk allergy model...
October 2018: Nutrition Research
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