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https://www.readbyqxmd.com/read/29779229/codeinone-reductase-isoforms-with-differential-stability-efficiency-and-product-selectivity-in-opium-poppy
#1
Mehran Dastmalchi, Limei Chang, Miguel A Torres, Kenneth K S Ng, Peter J Facchini
Codeinone reductase (COR) catalyzes the reversible NADPH-dependent reduction of codeinone to codeine as the penultimate step of morphine biosynthesis in opium poppy (Papaver somniferum). COR also irreversibly reduces neopinone, which forms by spontaneous isomerization in aqueous solution from codeinone, to neopine. In a parallel pathway involving 3-O-desmethylated analogs, COR converts morphinone to morphine, and neomorphinone to neomorphine. Similar to neopine, neomorphine formation by COR is irreversible...
May 19, 2018: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/29779193/functional-role-of-tyr12-in-the-catalytic-activity-of-novel-zeta-like-glutathione-s-transferase-from-acidovorax-sp-kks102
#2
Dayyabu Shehu, Zazali Alias
Glutathione S-transferases (GSTs) are a family of enzymes that function in the detoxification of variety of electrophilic substrates. In the present work, we report a novel zeta-like GST (designated as KKSG9) from the biphenyl/polychlorobiphenyl degrading organism Acidovorax sp. KKS102. KKSG9 possessed low sequence similarity but similar biochemical properties to zeta class GSTs. Functional analysis showed that the enzyme exhibits wider substrate specificity compared to most zeta class GSTs by reacting with 1-chloro-2,4-dinitrobenzene (CDNB), p-nitrobenzyl chloride (NBC), ethacrynic acid (EA), hydrogen peroxide, and cumene hydroperoxide...
May 19, 2018: Protein Journal
https://www.readbyqxmd.com/read/29778688/molecular-basis-of-diseases-caused-by-the-mtdna-mutation-m-8969g-a-in-the-subunit-a-of-atp-synthase
#3
Natalia Skoczeń, Alain Dautant, Krystyna Binko, François Godard, Marine Bouhier, Xin Su, Jean-Paul Lasserre, Marie-France Giraud, Déborah Tribouillard-Tanvier, Huimei Chen, Jean-Paul di Rago, Roza Kucharczyk
The ATP synthase which provides aerobic eukaryotes with ATP, organizes into a membrane-extrinsic catalytic domain, where ATP is generated, and a membrane-embedded FO domain that shuttles protons across the membrane. We previously identified a mutation in the mitochondrial MT-ATP6 gene (m.8969G>A) in a 14-year-old Chinese female who developed an isolated nephropathy followed by brain and muscle problems. This mutation replaces a highly conserved serine residue into asparagine at amino acid position 148 of the membrane-embedded subunit a of ATP synthase...
May 17, 2018: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29778536/enhanced-pkmt-substrate-recognition-through-non-active-site-interactions
#4
Margarita Kublanovsky, Amir Aharoni, Dan Levy
Protein lysine methyltransferases (PKMTs) catalyze the methylation of lysine residues on many different cellular proteins. Despite extensive biochemical and structural studies, focusing on PKMT active site-peptide interactions, little is known regarding how PKMTs recognize globular substrates. To examine whether these enzymes recognize protein substrates through interactions that take place outside of the active site, we have measured SETD6 and SETD7 activity with both protein and peptide RelA substrate. We have utilized the MTase-Glo™ methyltransferase assay to measure the activity of SETD6 and SETD7 with the different RelA substrates and calculated the Michaelis-Menten (MM) parameters...
May 17, 2018: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29775751/expression-pattern-and-functional-analysis-of-the-two-ring-box-protein-rbx-in-spermatogenesis-of-chinese-mitten-crab-eriocheir-sinensis
#5
Jia-Shun Zhang, Xue-Jie Li, Lei Yang, Wei-Wei Li, Qun Wang
Studies in E. sinensis have shown that ubiquitination mediated by Cullin-RING E3 ligases (CRLs) plays important roles in spermatogenesis. In other species, CRLs are also essential in cell cycle progression, DNA replication, signal transduction, gene transcription, and development. The catalytic RING component, the RING box protein, is an important part of CRLs. However, there have been few studies on CRLs in crustaceans. In this study, we cloned two RING box protein genes from the Chinese mitten crab, Eriocheir sinensis, termed Es-RBX1 and Es-RBX2 The full length Es-RBX1 cDNA comprises 741 nucleotides, and encodes a protein of 124 amino acid residues, whereas the Es-RBX2 cDNA comprises 1325 nucleotides, and encodes a protein of 110 amino acid residues...
May 15, 2018: Gene
https://www.readbyqxmd.com/read/29775743/redox-regulation-of-protein-kinase-c-by-selenometabolites-and-selenoprotein-thioredoxin-reductase-limits-cancer-prevention-by-selenium
#6
REVIEW
Rayudu Gopalakrishna, Usha Gundimeda, Sarah Zhou, Bui Helena, Arne Holmgren
The cancer-preventive mechanism of selenium should address the way low concentrations of selenometabolites react with cellular targets without being diffused from the sites of generation, the way selenium selectively kills tumor cells, and the intriguing U-shaped curve that is seen with dietary supplementation of selenium and cancer prevention. Protein kinase C (PKC), a receptor for tumor promoters, is well suited for this mechanism. Due to the catalytic redox cycle, low concentrations of methylselenol, a postulated active metabolite of selenium, react with the tumor-promoting lipid hydroperoxide bound to PKC to form methylseleninic acid (MSA), which selectively reacts with thiol residues present within the vicinity of the PKC catalytic domain to inactivate it...
May 15, 2018: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/29775713/enhancement-of-catalytic-activity-and-thermostability-of-a-thermostable-cellobiohydrolase-from-chaetomium-thermophilum-by-site-directed-mutagenesis
#7
Chao Han, Weiguang Li, Chengyao Hua, Fengqing Sun, Pengsheng Bi, Qunqing Wang
Enzymatic saccharification of lignocellulosic biomass is increasingly applied in agricultural and industrial applications. Nevertheless, low performance in the extreme environment severely prevents the utilization of commercial enzyme preparations. To obtain cellobiohydrolases with improved catalytic activity and thermostability, structure-based rational design was performed based on a thermostable cellobiohydrolase CtCel6 from Chaetomium thermophilum. In the present study, four conserved and noncatalytic residue substitutions were generated via site-directed mutagenesis...
May 15, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29775286/multiple-architectures-and-mechanisms-of-latency-in-metallopeptidase-zymogens
#8
Joan L Arolas, Theodoros Goulas, Anna Cuppari, F Xavier Gomis-Rüth
Metallopeptidases cleave polypeptides bound in the active-site cleft of catalytic domains through a general base/acid mechanism. This involves a solvent molecule bound to a catalytic zinc and general regulation of the mechanism through zymogen-based latency. Sixty reported structures from 11 metallopeptidase families reveal that prosegments, mostly N-terminal of the catalytic domain, block the cleft regardless of their size. Prosegments may be peptides (5-14 residues), which are only structured within the zymogens, or large moieties (<227 residues) of one or two folded domains...
May 18, 2018: Chemical Reviews
https://www.readbyqxmd.com/read/29773673/lysosomal-proteome-and-secretome-analysis-identifies-missorted-enzymes-and-their-non-degraded-substrates-in-mucolipidosis-iii-mouse-cells
#9
Giorgia Di Lorenzo, Renata Voltolini Velho, Dominic Winter, Melanie Thelen, Shiva Ahmadi, Michaela Schweizer, Raffaella De Pace, Kerstin Cornils, Timur Alexander Yorgan, Saskia Grüb, Irm Hermans-Borgmeyer, Thorsten Schinke, Sven Müller-Loennies, Thomas Braulke, Sandra Pohl
Targeting of soluble lysosomal enzymes requires mannose 6-phosphate (M6P) signals whose formation is initiated by the hexameric N-acetylglucosamine (GlcNAc)-1-phosphotransferase complex (α2β2γ2). Upon proteolytic cleavage by site-1 protease, the α/β-subunit precursor is catalytically activated but the functions of γ-subunits (Gnptg) in M6P modification of lysosomal enzymes are unknown. To investigate this, we analyzed the Gnptg expression in mouse tissues, primary cultured cells, and in Gnptg reporter mice in vivo, and found high amounts in the brain, eye, kidney, femur, vertebra and fibroblasts...
May 17, 2018: Molecular & Cellular Proteomics: MCP
https://www.readbyqxmd.com/read/29773654/genetic-code-expansion-and-live-cell-imaging-reveal-that-thr308-phosphorylation-is-irreplaceable-and-sufficient-for-akt1-activity
#10
Nileeka Balasuriya, Maya T Kunkel, Xuguang Liu, Kyle K Biggar, Shawn S-C Li, Alexandra C Newton, Patrick O'Donoghue
The proto-oncogene Akt/protein kinase B (PKB) is a pivotal signal transducer for growth and survival. Growth factor stimulation leads to Akt phosphorylation at two regulatory sites (Thr308, Ser473), acutely activating Akt signaling. Delineating the exact role of each regulatory site is, however, technically challenging and has remained elusive. Here, we used genetic code expansion to produce site-specifically phosphorylated Akt1 in order to dissect the contribution of each regulatory site to Akt1 activity. We achieved recombinant production of full length Akt1 containing site-specific pThr and pSer residues for the first time...
May 17, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29772260/oxime-assisted-reactivation-of-tabun-inhibited-acetylcholinesterase-analysed-by-active-site-mutations
#11
Maja Katalinić, Goran Šinko, Nikolina Maček Hrvat, Tamara Zorbaz, Anita Bosak, Zrinka Kovarik
The antidotal property of oximes is attributed to their ability to reactivate acetylcholinesterase (AChE) inhibited by organophosphorus compounds (OP) such as pesticides and nerve warfare agents. Understanding their interactions within the active site of phosphylated AChE is of great significance for the search for more efficient reactivators, especially in the case of the most resistant OP to reactivation, tabun. Therefore, herein we studied the interactions and reactivation of tabun-inhibited AChE by site-directed mutagenesis and a series of bispyridinium oximes...
May 14, 2018: Toxicology
https://www.readbyqxmd.com/read/29772182/oxidation-of-cr-iii-fe-iii-mixed-phase-hydroxides-by-chlorine-implications-on-the-control-of-hexavalent-chromium-in-drinking-water
#12
Michelle Chebeir, Haizhou Liu
The occurrence of chromium (Cr) as an inorganic contaminant in drinking water is widely reported. One source of Cr is its accumulation in iron-containing corrosion scales of drinking water distribution systems as Cr(III)-Fe(III) hydroxide, i.e., FexCr(1-x)(OH)3(s), where x represents the Fe(III) molar content and typically varies between 0.25 and 0.75. This study investigated the kinetics of inadvertent hexavalent chromium Cr(VI) formation via the oxidation of FexCr(1-x)(OH)3(s) by chlorine as a residual disinfectant in drinking water, and examined the impacts of Fe(III) content and drinking water chemical parameters including pH, bromide and bicarbonate on the rate of Cr(VI) formation...
May 17, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29767996/nanoscale-probing-of-local-hydrogen-heterogeneity-in-disordered-carbon-nitrides-with-vibrational-electron-energy-loss-spectroscopy
#13
Diane M Haiber, Peter A Crozier
In graphitic carbon nitrides, (photo)catalytic functionality is underpinned by the effect that residual hydrogen content, manifesting in amine (N-Hx ) defects, has on its optoelectronic properties. Therefore, a detailed understanding of the variation in the local structure of graphitic carbon nitrides is key for understanding structure-activity relationships. Here we apply aloof-beam vibrational electron energy-loss spectroscopy in the scanning transmission electron microscope (STEM) to locally detect variations in hydrogen content in two different layered carbon nitrides with nanometer resolution...
May 16, 2018: ACS Nano
https://www.readbyqxmd.com/read/29767194/qm-mm-simulations-identify-the-determinants-of-catalytic-activity-differences-between-type-ii-dehydroquinase-enzymes
#14
Emilio Lence, Marc W van der Kamp, Concepción González-Bello, Adrian J Mulholland
Type II dehydroquinase enzymes (DHQ2), recognized targets for antibiotic drug discovery, show significantly different activities dependent on the species: DHQ2 from Mycobacterium tuberculosis (MtDHQ2) and Helicobacter pylori (HpDHQ2) show a 50-fold difference in catalytic efficiency. Revealing the determinants of this activity difference is important for our understanding of biological catalysis and further offers the potential to contribute to tailoring specificity in drug design. Molecular dynamics simulations using a quantum mechanics/molecular mechanics potential, with correlated ab initio single point corrections, identify and quantify the subtle determinants of the experimentally observed difference in efficiency...
May 16, 2018: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29764512/mutational-analysis-of-two-residues-in-the-dyrk-homology-box-of-the-protein-kinase-dyrk1a
#15
Esti Wahyu Widowati, Simone Bamberg-Lemper, Walter Becker
OBJECTIVE: Dual specificity tyrosine phosphorylation-regulated kinases (DYRK) contain a characteristic sequence motif (DYRK homology box, DH box) that is located N-terminal of the catalytic domain and supports the autophosphorylation of a conserved tyrosine during maturation of the catalytic domain. Two missense mutations in the DH box of human DYRK1B were recently identified as causative of a rare familiar form of metabolic syndrome. We have recently shown that these amino acid exchanges impair maturation of the kinase domain...
May 15, 2018: BMC Research Notes
https://www.readbyqxmd.com/read/29761378/inhibition-and-substrate-specificity-properties-of-fkbp22-from-a-psychrotrophic-bacterium-shewanella-sp-sib1
#16
Cahyo Budiman, Herman Umbau Lindang, Bo Eng Cheong, Kenneth F Rodrigues
SIB1 FKBP22 is a peptidyl prolyl cis-trans isomerase (PPIase) member from a psychrotrophic bacterium, Shewanella sp. SIB1, consisting of N- and C-domains responsible for dimerization and catalytic PPIase activity, respectively. This protein was assumed to be involved in cold adaptation of SIB1 cells through its dual activity of PPIase activity and chaperone like-function. Nevertheless, the catalytic inhibition by FK506 and its substrate specificity remain unknown. Besides, ability of SIB1 FKBP22 to inhibit phosphatase activity of calcinuerin is also interesting to be studied since it may reflect wider cellular functions of SIB1 FKBP22...
May 14, 2018: Protein Journal
https://www.readbyqxmd.com/read/29761210/biochemical-properties-of-bacterial-reverse-transcriptase-related-rvt-gene-products-multimerization-protein-priming-and-nucleotide-preference
#17
Irina A Yushenova, Irina R Arkhipova
Cellular reverse transcriptase-related (rvt) genes represent a novel class of reverse transcriptases (RTs), which are only distantly related to RTs of retrotransposons and retroviruses, but, similarly to telomerase RTs, are immobilized in the genome as single-copy genes. They have been preserved by natural selection throughout the evolutionary history of large taxonomic groups, including most fungi, a few plants and invertebrates, and even certain bacteria, being the only RTs present across different domains of life...
May 14, 2018: Current Genetics
https://www.readbyqxmd.com/read/29758256/reduction-of-protein-kinase-a-mediated-phosphorylation-of-atxn1-s776-in-purkinje-cells-delays-onset-of-ataxia-in-a-sca1-mouse-model
#18
Judit M Pérez Ortiz, Nissa Mollema, Nicholas Toker, Carolyn J Adamski, Brennon O'Callaghan, Lisa Duvick, Jillian Friedrich, Michael A Walters, Jessica Strasser, Jon E Hawkinson, Huda Y Zoghbi, Christine Henzler, Harry T Orr, Sarita Lagalwar
Spinocerebellar ataxia type 1 (SCA1) is a polyglutamine (polyQ) repeat neurodegenerative disease in which a primary site of pathogenesis are cerebellar Purkinje cells. In addition to polyQ expansion of ataxin-1 protein (ATXN1), phosphorylation of ATXN1 at the serine 776 residue (ATXN1-pS776) plays a significant role in protein toxicity. Utilizing a biochemical approach, pharmacological agents and cell-based assays, including SCA1 patient iPSC-derived neurons, we examine the role of Protein Kinase A (PKA) as an effector of ATXN1-S776 phosphorylation...
May 11, 2018: Neurobiology of Disease
https://www.readbyqxmd.com/read/29758058/structural-studies-and-molecular-dynamics-simulations-suggest-a-processive-mechanism-of-exolytic-lytic-transglycosylase-from-campylobacter-jejuni
#19
Jagamya Vijayaraghavan, Vijay Kumar, Nikhil P Krishnan, Ross T Kaufhold, Ximin Zeng, Jun Lin, Focco van den Akker
The bacterial soluble lytic transglycosylase (LT) breaks down the peptidoglycan (PG) layer during processes such as cell division. We present here crystal structures of the soluble LT Cj0843 from Campylobacter jejuni with and without bulgecin A inhibitor in the active site. Cj0843 has a doughnut shape similar but not identical to that of E. coli SLT70. The C-terminal catalytic domain is preceded by an L-domain, a large helical U-domain, a flexible linker, and a small N-terminal NU-domain. The flexible linker allows the NU-domain to reach over and complete the circular shape, using residues conserved in the Epsilonproteobacteria LT family...
2018: PloS One
https://www.readbyqxmd.com/read/29757624/steric-control-of-the-rate-limiting-step-of-udp-galactopyranose-mutase
#20
Gustavo Pierdominici-Sottile, Rodrigo Cossio-P Eacute Rez, Isabel Da Fonseca, Karina Kizjakina, John J Tanner, Pablo Sobrado
Galactose is an abundant monosaccharide found exclusively in mammals as galactopyranose (Galp), the six-membered ring form of this sugar. In contrast, galactose appears in many pathogenic microorganisms as the five-membered ring form, galactofuranose (Galf). Galf biosynthesis begins with the conversion of UDP-Galp to UDP-Galf catalyzed by the flavoenzyme UDP-galactopyranose mutase (UGM). Because UGM is essential for the survival and proliferation of several pathogens, there is interest in understanding the catalytic mechanism to aid inhibitor development...
May 14, 2018: Biochemistry
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