کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8270874 1534979 2013 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Myeloperoxidase acts as a source of free iron during steady-state catalysis by a feedback inhibitory pathway
ترجمه فارسی عنوان
میلوپروکسیداز به عنوان یک منبع آهن آزاد در طی کاتالیزوری حالت پایدار به وسیله مسیر مهار بازده ای عمل می کند
کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی سالمندی
چکیده انگلیسی
Myeloperoxidase (MPO) is a heme-containing enzyme that generates hypochlorous acid (HOCl) from chloride (Cl−) and hydrogen peroxide (H2O2). It is implicated in the pathology of several chronic inflammatory conditions such as cardiovascular and pulmonary diseases and cancer. Recently we have shown that HOCl can destroy the heme prosthetic group of hemoproteins. Here, we investigated whether the HOCl formed during steady-state catalysis is able to destroy the MPO heme moiety and thereby function as a major source of free iron. UV-visible spectra and H2O2-specific electrode measurements recorded during steady-state HOCl synthesis by MPO showed that the degree of MPO heme destruction increased after multiple additions of H2O2 (10 µM), precluding the enzyme from functioning at maximum activity (80-90% inhibition). MPO heme destruction occurred only in the presence of Cl−. Stopped-flow measurements revealed that the HOCl-mediated MPO heme destruction was complex and occurred through transient ferric species whose formation and decay kinetics indicated it participates in heme destruction along with subsequent free iron release. MPO heme depletion was confirmed by the buildup of free iron utilizing the ferrozine assay. Hypochlorous acid, once generated, first equilibrates in the solution as a whole before binding to the heme iron and initiating heme destruction. Eliminating HOCl from the MPO milieu by scavenging HOCl, destabilizing the MPO-Compound I-Cl complex that could be formed during catalysis, and/or inhibiting MPO catalytic activity partially or completely protects MPO from HOCl insults. Collectively, this study elucidates the bidirectional relationship between MPO and HOCl, which highlights the potential role of MPO as a source of free iron.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Free Radical Biology and Medicine - Volume 63, October 2013, Pages 90-98
نویسندگان
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