کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1316727 976477 2007 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Electrochemical reduction of ferrous α-verdoheme in complex with heme oxygenase-1
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Electrochemical reduction of ferrous α-verdoheme in complex with heme oxygenase-1
چکیده انگلیسی

The heme oxygenase (HO) reaction consists of three successive oxygenation reactions, i.e. heme to α-hydroxyheme, α-hydroxyheme to verdoheme, and verdoheme to biliverdin–iron chelate. Of these, the least understood step is the conversion of verdoheme to biliverdin–iron chelate. For the cleavage of the oxaporphyrin ring of ferrous verdoheme, involvement of a verdoheme π-neutral radical has been proposed. To probe this hypothetical mechanism in the HO reaction, we performed electrochemical reduction of ferrous verdoheme complexed with rat HO-1 under anaerobic conditions. On the basis of the electrochemical spectral changes, the midpoint potential for the one-electron reduction of the oxaporphyrin ring of ferrous verdoheme was found to be −0.47 ± 0.01 V vs the normal hydrogen electrode (NHE). Because this potential is far lower than those of both flavins of NADPH-cytochrome P450 reductase, and of NADPH, it is concluded that the one-electron reduction of the oxaporphyrin ring of ferrous verdoheme is unlikely to occur and that the formation of the π-neutral radical cannot be the initial step in the degradation of verdoheme by HO. Rather, it appears more reasonable to consider an alternative mechanism in which binding of O2 to the ferrous iron of verdoheme is the first step in the degradation of verdoheme.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Inorganic Biochemistry - Volume 101, Issue 10, October 2007, Pages 1394–1399
نویسندگان
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