کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1926055 1536432 2010 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Mechanisms of catalase activity of heme peroxidases
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Mechanisms of catalase activity of heme peroxidases
چکیده انگلیسی

In the absence of exogenous electron donors monofunctional heme peroxidases can slowly degrade hydrogen peroxide following a mechanism different from monofunctional catalases. This pseudo-catalase cycle involves several redox intermediates including Compounds I, II and III, hydrogen peroxide reduction and oxidation reactions as well as release of both dioxygen and superoxide. The rate of decay of oxyferrous complex determines the rate-limiting step and the enzymes’ resistance to inactivation. Homologous bifunctional catalase-peroxidases (KatGs) are unique in having both a peroxidase and high hydrogen dismutation activity without inhibition reactions. It is demonstrated that KatGs follow a similar reaction pathway as monofunctional peroxidases, but use a unique post-translational distal modification (Met+-Tyr-Trp adduct) in close vicinity to the heme as radical site that enhances turnover of oxyferrous heme and avoids release of superoxide. Similarities and differences between monofunctional peroxidases and bifunctional KatGs are discussed and mechanisms of pseudo-catalase activity are proposed.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Archives of Biochemistry and Biophysics - Volume 500, Issue 1, 1 August 2010, Pages 74–81
نویسندگان
, , , , , ,