کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1178902 | 962739 | 2010 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Probing hydrogen peroxide oxidation kinetics of wild-type Synechocystis catalase-peroxidase (KatG) and selected variants
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کلمات کلیدی
PAAPORBLCADD - اضافه کردنHydrogen peroxide oxidation - اکسیداسیون پراکسید هیدروژنCompound I - ترکیب IStopped-flow spectroscopy - طیف سنجی جریان متوقف شدهCatalase activity - فعالیت کاتالازkon - می تواندPorphyrin - پورفیرینCyanide complex - پیچیده سیانیدCatalase-peroxidase - کاتالاز پراکسیدازBovine liver catalase - کاتالاز کبدی گاوHydrogen peroxide reduction - کاهش پراکسید هیدروژنkatG - کت
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Catalase-peroxidases (KatGs) are unique bifunctional heme peroxidases that exhibit peroxidase and substantial catalase activities. Nevertheless, the reaction pathway of hydrogen peroxide dismutation, including the electronic structure of the redox intermediate that actually oxidizes H2O2, is not clearly defined. Several mutant proteins with diminished overall catalase but wild-type-like peroxidase activity have been described in the last years. However, understanding of decrease in overall catalatic activity needs discrimination between reduction and oxidation reactions of hydrogen peroxide. Here, by using sequential-mixing stopped-flow spectroscopy, we have investigated the kinetics of the transition of KatG compound I (produced by peroxoacetic acid) to its ferric state by trapping the latter as cyanide complex. Apparent bimolecular rate constants (pH 6.5, 20 °C) for wild-type KatG and the variants Trp122Phe (lacks KatG-typical distal adduct), Asp152Ser (controls substrate access to the heme cavity) and Glu253Gln (channel entrance) are reported to be 1.2 Ã 104 Mâ 1 sâ 1, 30 Mâ 1 sâ 1, 3.4 Ã 103 Mâ 1 sâ 1, and 8.6 Ã 103 Mâ 1 sâ 1, respectively. These findings are discussed with respect to steady-state kinetic data and proposed reaction mechanism(s) for KatG. Assets and drawbacks of the presented method are discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics - Volume 1804, Issue 4, April 2010, Pages 799-805
Journal: Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics - Volume 1804, Issue 4, April 2010, Pages 799-805
نویسندگان
Jutta Vlasits, Paul G. Furtmüller, Christa Jakopitsch, Marcel Zamocky, Christian Obinger,