کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
221240 463380 2007 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of axial ligand mutation of the type I copper site in bilirubin oxidase on direct electron transfer-type bioelectrocatalytic reduction of dioxygen
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Effects of axial ligand mutation of the type I copper site in bilirubin oxidase on direct electron transfer-type bioelectrocatalytic reduction of dioxygen
چکیده انگلیسی

Direct electron transfer (DET)-type electrocatalytic properties were examined for a site-directed mutant (M467Q) of Myrothecium verrucaria bilirubin oxidase (BOD), in which Met467 as the axial ligand of the type I copper site is replaced by Gln. Although the enzymatic activity of the mutant is very low toward bilirubin [A. Shimizu, et al., J. Biochem. 125 (1999) 662–668], it works as a good catalyst in DET-type bioelectrocatalytic reduction of dioxygen into water. The wave appears around the formal potential of the type I Cu site, which is about 0.23 V more negative than that of the wild-type recombinant (rBOD), and the catalytic limiting current density is larger than that of rBOD. Detailed analysis of the voltammograms and the enzyme kinetics suggests that the electrons are transferred from electrodes to the type I Cu site and that the mutation does not injure the kinetics of the three processes: the heterogeneous electron transfer, the intramolecular electron transfer from the type I Cu site to the trinuclear type II–III Cu cluster, and the catalytic process to reduce dioxygen at the type II–III Cu cluster. The overall catalytic constant is increased by the mutation. This result can be interpreted in terms of the increased Gibbs energy difference in the electron transfer reaction from the type I Cu site to the type II–III Cu cluster.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Electroanalytical Chemistry - Volume 601, Issues 1–2, 15 March 2007, Pages 119–124
نویسندگان
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