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  1 / 25937 MEDLINE  
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[PMID]:28747400
[Au] Autor:Gupta A; Milias-Argeitis A; Khammash M
[Ad] Endereço:Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland.
[Ti] Título:Dynamic disorder in simple enzymatic reactions induces stochastic amplification of substrate.
[So] Source:J R Soc Interface;14(132), 2017 Jul.
[Is] ISSN:1742-5662
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:A growing amount of evidence over the last two decades points to the fact that many enzymes exhibit fluctuations in their catalytic activity, which are associated with conformational changes on a broad range of timescales. The experimental study of this phenomenon, termed dynamic disorder, has become possible thanks to advances in single-molecule enzymology measurement techniques, through which the catalytic activity of individual enzyme molecules can be tracked in time. The biological role and importance of these fluctuations in a system with a small number of enzymes, such as a living cell, have only recently started being explored. In this work, we examine a simple stochastic reaction system consisting of an inflowing substrate and an enzyme with a randomly fluctuating catalytic reaction rate that converts the substrate into an outflowing product. To describe analytically the effect of rate fluctuations on the average substrate abundance at steady state, we derive an explicit formula that connects the relative speed of enzymatic fluctuations with the mean substrate level. Under fairly general modelling assumptions, we demonstrate that the relative speed of rate fluctuations can have a dramatic effect on the mean substrate, and lead to large positive deviations from predictions based on the assumption of deterministic enzyme activity. Our results also establish an interesting connection between the amplification effect and the mixing properties of the Markov process describing the enzymatic activity fluctuations, which can be used to easily predict the fluctuation speed above which such deviations become negligible. As the techniques of single-molecule enzymology continuously evolve, it may soon be possible to study the stochastic phenomena due to enzymatic activity fluctuations within living cells. Our work can be used to formulate experimentally testable hypotheses regarding the nature and magnitude of these fluctuations, as well as their phenotypic consequences.
[Mh] Termos MeSH primário: Enzimas/metabolismo
Modelos Biológicos
[Mh] Termos MeSH secundário: Simulação por Computador
Enzimas/química
Cinética
Conformação Proteica
Processos Estocásticos
Especificidade por Substrato
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Enzymes)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180228
[Lr] Data última revisão:
180228
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170728
[St] Status:MEDLINE


  2 / 25937 MEDLINE  
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[PMID]:29293684
[Au] Autor:Vera LM; Bello C; Paredes JF; Carmona-Antoñanzas G; Sánchez-Vázquez FJ
[Ad] Endereço:Department of Physiology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Murcia, Spain.
[Ti] Título:Ethanol toxicity differs depending on the time of day.
[So] Source:PLoS One;13(1):e0190406, 2018.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Ethanol is one of the most commonly abused drugs and consequently its toxic and psychoactive effect has been widely investigated, although little is known about the time-dependent effects of this drug. In the present research zebrafish was used to assess daily rhythms in ethanol toxicity and behavioural effects, as well as the temporal pattern of expression of key genes involved in ethanol detoxification in the liver (adh8a, adh5, aldh2.1 and aldh2.2). Our results showed marked differences in the mortality rate of zebrafish larvae depending on the time of day of the exposure to 5% ethanol for 1h (82% and 6% mortality in the morning and at night, respectively). A significant daily rhythm was detected with the acrophase located at "zeitgeber" time (ZT) = 04:22 h. Behavioural tests exposing zebrafish to 1% ethanol provoked a major decrease in swimming activity (68-84.2% reduction) at ZT2, ZT6 and ZT10. In contrast, exposure at ZT18 stimulated swimming activity (27% increase). During the day fish moved towards the bottom of the tank during ethanol exposure, whereas at night zebrafish increased their activity levels right after the exposure to ethanol. Genes involved in ethanol detoxification failed to show significant daily rhythms in LD, although all of them exhibited circadian regulation in constant darkness (DD) with acrophases in phase and located at the end of the subjective night. Taken altogether, this research revealed the importance of considering the time of day when designing and carrying out toxicological and behavioural tests to investigate the effects of ethanol, as the adverse effects of this drug were more marked when fish were exposed in the morning than at night.
[Mh] Termos MeSH primário: Ritmo Circadiano
Etanol/toxicidade
[Mh] Termos MeSH secundário: Animais
Comportamento Animal
Enzimas/genética
Expressão Gênica
Natação
Peixe-Zebra
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Enzymes); 3K9958V90M (Ethanol)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180221
[Lr] Data última revisão:
180221
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180103
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0190406


  3 / 25937 MEDLINE  
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[PMID]:29293520
[Au] Autor:Padgett LR; Lentini JM; Holmes MJ; Stilger KL; Fu D; Sullivan WJ
[Ad] Endereço:Department of Pharmacology & Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
[Ti] Título:Elp3 and RlmN: A tale of two mitochondrial tail-anchored radical SAM enzymes in Toxoplasma gondii.
[So] Source:PLoS One;13(1):e0189688, 2018.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Radical S-adenosylmethionine (rSAM) enzymes use a 5'-deoxyadensyl 5'-radical to methylate a wide array of diverse substrates including proteins, lipids and nucleic acids. One such enzyme, Elongator protein-3 (TgElp3), is an essential protein in Toxoplasma gondii, a protozoan parasite that can cause life-threatening opportunistic disease. Unlike Elp3 homologues which are present in all domains of life, TgElp3 localizes to the outer mitochondrial membrane (OMM) via a tail-anchored trafficking mechanism in Toxoplasma. Intriguingly, we identified a second tail-anchored rSAM domain containing protein (TgRlmN) that also localizes to the OMM. The transmembrane domain (TMD) on Toxoplasma Elp3 and RlmN homologues is required for OMM localization and has not been seen beyond the chromalveolates. Both TgElp3 and TgRlmN contain the canonical rSAM amino acid sequence motif (CxxxCxxC) necessary to form the 4Fe-4S cluster required for tRNA modifications. In E. coli, RlmN is responsible for the 2-methlyadenosine (m2A) synthesis at purine 37 in tRNA while in S. cerevisiae, Elp3 is necessary for the formation of 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) at the wobble tRNA position. To investigate why these two rSAM enzymes localize to the mitochondrion in Toxoplasma, and whether or not TgRlmN and TgElp3 possess tRNA methyltransferase activity, a series of mutational and biochemical studies were performed. Overexpression of either TgElp3 or TgRlmN resulted in a significant parasite replication defect, but overexpression was tolerated if either the TMD or rSAM domain was mutated. Furthermore, we show the first evidence that Toxoplasma tRNAGlu contains the mcm5s2U modification, which is the putative downstream product generated by TgElp3 activity.
[Mh] Termos MeSH primário: Enzimas/metabolismo
Proteínas de Protozoários/metabolismo
Toxoplasma/enzimologia
[Mh] Termos MeSH secundário: Toxoplasma/crescimento & desenvolvimento
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, U.S. GOV'T, P.H.S.
[Nm] Nome de substância:
0 (Enzymes); 0 (Protozoan Proteins)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180215
[Lr] Data última revisão:
180215
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180103
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0189688


  4 / 25937 MEDLINE  
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[PMID]:29293506
[Au] Autor:Choi JE; Nguyen CM; Lee B; Park JH; Oh JY; Choi JS; Kim JC; Song JK
[Ad] Endereço:Research Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), Daejeon, Republic of Korea.
[Ti] Título:Isolation and characterization of a novel metagenomic enzyme capable of degrading bacterial phytotoxin toxoflavin.
[So] Source:PLoS One;13(1):e0183893, 2018.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Toxoflavin, a 7-azapteridine phytotoxin produced by the bacterial pathogens such as Burkholderia glumae and Burkholderia gladioli, has been known as one of the key virulence factors in crop diseases. Because the toxoflavin had an antibacterial activity, a metagenomic E. coli clone capable of growing well in the presence of toxoflavin (30 µg/ml) was isolated and the first metagenome-derived toxoflavin-degrading enzyme, TxeA of 140 amino acid residues, was identified from the positive E. coli clone. The conserved amino acids for metal-binding and extradiol dioxygenase activity, Glu-12, His-8 and Glu-130, were revealed by the sequence analysis of TxeA. The optimum conditions for toxoflavin degradation were evaluated with the TxeA purified in E. coli. Toxoflavin was totally degraded at an initial toxoflavin concentration of 100 µg/ml and at pH 5.0 in the presence of Mn2+, dithiothreitol and oxygen. The final degradation products of toxoflavin and methyltoxoflavin were fully identified by MS and NMR as triazines. Therefore, we suggested that the new metagenomic enzyme, TxeA, provided the clue to applying the new metagenomic enzyme to resistance development of crop plants to toxoflavin-mediated disease as well as to biocatalysis for Baeyer-Villiger type oxidation.
[Mh] Termos MeSH primário: Toxinas Bacterianas/metabolismo
Burkholderia/metabolismo
Enzimas/metabolismo
Metagenômica
Pirimidinonas/metabolismo
Triazinas/metabolismo
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Homologia de Sequência de Aminoácidos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Bacterial Toxins); 0 (Enzymes); 0 (Pyrimidinones); 0 (Triazines); 5N5YI4IP1P (toxoflavin)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180215
[Lr] Data última revisão:
180215
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180103
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0183893


  5 / 25937 MEDLINE  
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[PMID]:29324770
[Au] Autor:Teng W; Kang Y; Hou W; Hu H; Luo W; Wei J; Wang L; Zhang B
[Ad] Endereço:Forestry College, Guangxi University, Nanning, Guangxi, China.
[Ti] Título:Phosphorus application reduces aluminum toxicity in two Eucalyptus clones by increasing its accumulation in roots and decreasing its content in leaves.
[So] Source:PLoS One;13(1):e0190900, 2018.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Under acidic conditions, aluminum (Al) toxicity is an important factor limiting plant productivity; however, the application of phosphorus (P) might alleviate the toxic effects of Al. In this study, seedlings of two vegetatively propagated Eucalyptus clones, E. grandis × E. urophylla 'G9' and E. grandis × E. urophylla 'DH32-29'were subjected to six treatments (two levels of Al stress and three levels of P). Under excessive Al stress, root Al content was higher, whereas shoot and leaf Al contents were lower with P application than those without P application. Further, Al accumulation was higher in the roots, but lower in the shoots and leaves of G9 than in those of DH32-29. The secretion of organic acids was higher under Al stress than under no Al stress. Further, under Al stress, the roots of G9 secreted more organic acids than those of DH32-29. With an increase in P supply, Al-induced secretion of organic acids from roots decreased. Under Al stress, some enzymes, including PEPC, CS, and IDH, played important roles in organic acid biosynthesis and degradation. Thus, our results indicate that P can reduce Al toxicity via the fixation of elemental Al in roots and restriction of its transport to stems and leaves, although P application cannot promote the secretion of organic acid anions. Further, the higher Al-resistance of G9 might be attributed to the higher Al accumulation in and organic acid anion secretion from roots and the lower levels of Al in leaves.
[Mh] Termos MeSH primário: Alumínio/toxicidade
Eucalyptus/efeitos dos fármacos
Eucalyptus/metabolismo
Fósforo/farmacologia
Folhas de Planta/metabolismo
Raízes de Plantas/metabolismo
Substâncias Protetoras/farmacologia
[Mh] Termos MeSH secundário: Compostos de Alumínio/farmacologia
Biomassa
Cloretos/farmacologia
Enzimas/metabolismo
Eucalyptus/genética
Fosfatos/administração & dosagem
Fosfatos/farmacologia
Fósforo/administração & dosagem
Folhas de Planta/efeitos dos fármacos
Proteínas de Plantas/metabolismo
Raízes de Plantas/efeitos dos fármacos
Caules de Planta/efeitos dos fármacos
Caules de Planta/metabolismo
Compostos de Potássio/administração & dosagem
Compostos de Potássio/farmacologia
Substâncias Protetoras/administração & dosagem
Distribuição Aleatória
Plântulas/efeitos dos fármacos
Plântulas/metabolismo
Estresse Fisiológico/efeitos dos fármacos
Estresse Fisiológico/fisiologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Aluminum Compounds); 0 (Chlorides); 0 (Enzymes); 0 (Phosphates); 0 (Plant Proteins); 0 (Potassium Compounds); 0 (Protective Agents); 27YLU75U4W (Phosphorus); 3CYT62D3GA (aluminum chloride); B7862WZ632 (potassium phosphate); CPD4NFA903 (Aluminum)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180206
[Lr] Data última revisão:
180206
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180112
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0190900


  6 / 25937 MEDLINE  
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[PMID]:27775883
[Au] Autor:Druart K; Bigot J; Audit E; Simonson T
[Ad] Endereço:Laboratoire de Biochimie (CNRS UMR7654), Ecole Polytechnique , Palaiseau, France.
[Ti] Título:A Hybrid Monte Carlo Scheme for Multibackbone Protein Design.
[So] Source:J Chem Theory Comput;12(12):6035-6048, 2016 Dec 13.
[Is] ISSN:1549-9626
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Multistate protein design explores side chain mutations, with the backbone allowed to sample a small, predetermined library of conformations. To achieve Boltzmann sampling of sequences and conformations, we use a hybrid Monte Carlo (MC) scheme: a trial hop between backbone models is followed by a short MC segment where side chain rotamers adjust to the new backbone, before applying a Metropolis-like acceptance test. The theoretical form and a practical approximation for the acceptance test are derived. We then compute backbone conformational free energies for two SH2 and SH3 proteins using different routes and protocols, and verify that for simple test problems, the free energy behaves like a state function, a hallmark of Boltzmann sampling.
[Mh] Termos MeSH primário: Proteínas/química
[Mh] Termos MeSH secundário: Domínio Catalítico
Enzimas/química
Enzimas/metabolismo
Simulação de Dinâmica Molecular
Método de Monte Carlo
Estrutura Terciária de Proteína
Proteínas/metabolismo
Termodinâmica
Domínios de Homologia de src
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Enzymes); 0 (Proteins)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180206
[Lr] Data última revisão:
180206
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161025
[St] Status:MEDLINE


  7 / 25937 MEDLINE  
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[PMID]:29220191
[Au] Autor:Zoi I; Antoniou D; Schwartz SD
[Ad] Endereço:Department of Biochemistry, University of Arizona , Tucson, Arizona 85721, United States.
[Ti] Título:Electric Fields and Fast Protein Dynamics in Enzymes.
[So] Source:J Phys Chem Lett;8(24):6165-6170, 2017 Dec 21.
[Is] ISSN:1948-7185
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:In recent years, there has been much discussion regarding the origin of enzymatic catalysis and whether including protein dynamics is necessary for understanding catalytic enhancement. An important contribution in this debate was made with the application of the vibrational Stark effect spectroscopy to measure electric fields in the active site. This provided a window on electric fields at the transition state in enzymatic reactions. We performed computational studies on two enzymes where we have shown that fast dynamics is part of the reaction mechanism and calculated the electric field near the bond-breaking event. We found that the fast motions that we had identified lead to an increase of the electric field, thus preparing an enzymatic configuration that is electrostatically favorable for the catalytic chemical step. We also studied the enzyme that has been the subject of Stark spectroscopy, ketosteroid isomerase, and found electric fields of a similar magnitude to the two previous examples.
[Mh] Termos MeSH primário: Enzimas/química
Conformação Proteica
Eletricidade Estática
[Mh] Termos MeSH secundário: Catálise
Domínio Catalítico
Eletricidade
Modelos Moleculares
Esteroide Isomerases
Vibração
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Enzymes); EC 5.3.3.- (Steroid Isomerases)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180205
[Lr] Data última revisão:
180205
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171209
[St] Status:MEDLINE
[do] DOI:10.1021/acs.jpclett.7b02989


  8 / 25937 MEDLINE  
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[PMID]:28463490
[Au] Autor:Tomita T; Kim SY; Teramoto K; Meguro A; Ozaki T; Yoshida A; Motoyoshi Y; Mori N; Ishigami K; Watanabe H; Nishiyama M; Kuzuyama T
[Ti] Título:Structural Insights into the CotB2-Catalyzed Cyclization of Geranylgeranyl Diphosphate to the Diterpene Cyclooctat-9-en-7-ol.
[So] Source:ACS Chem Biol;12(6):1621-1628, 2017 06 16.
[Is] ISSN:1554-8937
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The diterpene cyclase CotB2 catalyzes the cyclization of geranylgeranyl diphosphate (GGPP) to the tricyclic cyclooctat-9-en-7-ol, which is characterized by a 5-8-5-fused ring skeleton. We have previously proposed a cyclization cascade involving a unique carbon-carbon bond rearrangement combined with multiple hydride shifts, all occurring at a single active site. Here, we report the first high-resolution X-ray crystal structure of CotB2 with bound substrate analog geranylgeranyl thiodiphosphate (GGSPP). In the GGSPP-bound form, GGSPP folds into a unique S-shaped conformation that probably reflects the substrate-bound state prior to ionization of the substrate GGPP. The folded framework of GGSPP is surrounded by hydrophobic residues and several aromatic and asparagine residues that are well-positioned to stabilize a series of reactive carbocation intermediates through a combination of cation-π and dipole charge interactions. The combined crystal structures and mutagenesis-based biochemical assays provide a structural basis for exquisite control of ring formation and stereochemistry during CotB2 catalysis.
[Mh] Termos MeSH primário: Proteínas de Bactérias/metabolismo
Biocatálise
Diterpenos/química
Oxirredutases Intramoleculares/metabolismo
Fosfatos de Poli-Isoprenil/química
[Mh] Termos MeSH secundário: Proteínas de Bactérias/química
Cristalografia por Raios X
Ciclização
Ciclo-Octanos/química
Ciclo-Octanos/metabolismo
Enzimas/química
Enzimas/metabolismo
Mutagênese Sítio-Dirigida
Streptomyces/enzimologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Cyclooctanes); 0 (Diterpenes); 0 (Enzymes); 0 (Polyisoprenyl Phosphates); EC 5.3.- (Intramolecular Oxidoreductases); N21T0D88LX (geranylgeranyl pyrophosphate)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:180201
[Lr] Data última revisão:
180201
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170503
[St] Status:MEDLINE
[do] DOI:10.1021/acschembio.7b00154


  9 / 25937 MEDLINE  
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[PMID]:29172463
[Au] Autor:Zhou Y; Liu B; Yang R; Liu J
[Ad] Endereço:School of Chemistry and Biological Engineering, Changsha University of Science and Technology , Changsha 410114, P. R. China.
[Ti] Título:Filling in the Gaps between Nanozymes and Enzymes: Challenges and Opportunities.
[So] Source:Bioconjug Chem;28(12):2903-2909, 2017 Dec 20.
[Is] ISSN:1520-4812
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Using nanomaterials to mimic the function of protein enzymes is an interesting idea. Many nanomaterials have a similar size as enzymes and they also possess catalytic activity. Over the past decade, a surge of nanozyme work has emerged, likely due to the advancement in the synthesis and characterization of inorganic nanoparticles. Many typical enzymatic reactions mimicking oxidases, peroxidases, laccases, superoxide dismutases, and catalases have been realized by simple metal oxide and metal nanoparticles. In addition, small inorganic catalysts have been loaded in nanoparticles to create another type of nanozyme. The applications of nanozymes in biosensor design, environmental remediation, and therapeutics have been demonstrated. In this Topical Review, we briefly summarize the current status of the field and then focus our attention on some important problems faced by the field. These topics include developing better nanozymes with higher activity, better substrate selectivity, and engineering enzyme-like active sites. For practical applications, reliable methods for bioconjugation of nanozymes with affinity ligands need to be achieved, but not at the cost of losing the activity of nanozymes. Finally, fundamental mechanistic studies are needed to rationally design nanozymes and to obtain key insights into a few model systems.
[Mh] Termos MeSH primário: Biomimética/métodos
Enzimas/metabolismo
Nanoestruturas
Nanotecnologia/métodos
[Mh] Termos MeSH secundário: Enzimas/química
Nanoestruturas/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Enzymes)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180105
[Lr] Data última revisão:
180105
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171128
[St] Status:MEDLINE
[do] DOI:10.1021/acs.bioconjchem.7b00673


  10 / 25937 MEDLINE  
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[PMID]:29190764
[Au] Autor:Taylor RM; Sunde RA
[Ad] Endereço:Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin, United States of America.
[Ti] Título:Selenium requirements based on muscle and kidney selenoprotein enzyme activity and transcript expression in the turkey poult (Meleagris gallopavo).
[So] Source:PLoS One;12(11):e0189001, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The current NRC selenium (Se) requirement for turkeys is 0.2 µg Se/g diet. We previously fed turkey poults a Se-deficient diet (0.005 µg Se/g) supplemented with 10 graded levels of Se (0, 0.025, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0 µg Se/g as Na2SeO3, 5/treatment) for 4 wk, and found that the minimum dietary Se requirement was 0.3 µg Se/g based on selenoprotein enzyme activity in blood, liver, gizzard and pancreas. Because the turkey is primarily a production animal, we expanded this analysis to kidney, heart, breast and thigh. Se concentrations in Se-deficient poults were 5.0, 9.8, 33, and 15% of levels in poults fed 0.4 µg Se/g in liver, kidney, thigh and breast, respectively. Increasing Se supplementation resulted in hyperbolic response curves for all tissues; breakpoint analysis indicated minimum Se requirements of 0.34-0.36 µg Se/g based on tissue Se levels in liver, kidney and thigh. Similarly, GPX1 activity in muscle tissues and kidney responded hyperbolically to increasing dietary Se, reaching well-defined plateaus with breakpoints at 0.30-0.36 µg Se/g. Minimum Se requirements based on GPX4 activity were 0.30-0.32 µg Se/g for breast and thigh. Selenoprotein transcript expression decreased significantly in Se deficiency for only 2, 3, 5, and 6 mRNA in breast, thigh, heart, and kidney, respectively, out of 24 known avian selenoproteins. Se response curves for regulated selenoprotein transcripts were hyperbolic, and reached well-defined plateaus with breakpoints in a narrow range of 0.08-0.19 µg Se/g. No selenoprotein transcript was altered by supernutritional Se. In summary, these results clearly indicate that the NRC dietary Se requirement should be raised to 0.4 µg Se/g, at least for poults, to meet the nutritional needs of the young turkey. The Se response curve plateaus further show that limits for turkey supplementation with selenite could safely be raised to 0.5 µg Se/g diet.
[Mh] Termos MeSH primário: Enzimas/metabolismo
Rim/enzimologia
Músculos/enzimologia
RNA Mensageiro/genética
Selenoproteínas/metabolismo
[Mh] Termos MeSH secundário: Animais
Enzimas/genética
Turquia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Enzymes); 0 (RNA, Messenger); 0 (Selenoproteins)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180101
[Lr] Data última revisão:
180101
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171201
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0189001



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