کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9882404 | 1536557 | 2005 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The serine acetyltransferase reaction: acetyl transfer from an acylpantothenyl donor to an alcohol
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
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چکیده انگلیسی
Serine acetyltransferase is a member of the left-handed parallel β-helix family of enzymes that catalyzes the committed step in the de novo synthesis of l-cysteine in bacteria and plants. The enzyme has an ordered kinetic mechanism with acetyl CoA bound prior to l-serine and O-acetyl-l-serine released prior to CoA. The rate-limiting step along the reaction pathway is the nucleophilic attack of the serine hydroxyl on the thioester of acetyl CoA. Product release contributes to rate-limitation at saturating concentrations of reactants. The reaction is catalyzed by an active site general base with a pK of 7, which accepts a proton from the serine hydroxyl as a tetrahedral intermediate is formed between the reactants, and donates it to the thiol of CoA as the intermediate collapses to give products. This mechanism is likely the same for all O-acyltransferases that catalyze their reaction by direct attack of the alcohol on the acyl donor, using an active-site histidine as the general base. Serine acetyltransferase is regulated by feedback inhibition by the end product l-cysteine, which acts by binding to the serine site in the active site and inducing a conformational change that prevents reactant binding. The enzyme also associates with O-acetylserine sulfhydrylase, the final enzyme in the biosynthetic pathway, which contributes to stabilizing the acetyltransferase.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Archives of Biochemistry and Biophysics - Volume 433, Issue 1, 1 January 2005, Pages 85-95
Journal: Archives of Biochemistry and Biophysics - Volume 433, Issue 1, 1 January 2005, Pages 85-95
نویسندگان
Corey M. Johnson, Steven L. Roderick, Paul F. Cook,