A Model of the Heme Site of Cytochrome P-450 : Characterization of a Sulfhydryl- and Imidazole-containing Peptide-Heme System in Solution

概要

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The absorption and electron paramagnetic resonance (EPR) spectral properties of model systems consisting of sulfhydryl- and imidazole-containing peptides (mercaptoacetylhistidine, β-mercaptopropionylhistidine, mercaptoacetylglycylhistidine and mercaptoacetylalanylhistidine) and hemin were studied at pH 7.2. In these systems, mixed spin states of ferric heme were observed, and analysis of the EPR data indicated the formation of three different types of complex. Addition of pyridine to these systems caused a spin transition to a single type of low spin state ferric heme, indicating the formation of-S■-Fe (III)-N coordination. The ligand-field parameters of low spin species of the model systems were calculated and compared with those of cytochrome P-450. A possible reaction sequence and proposed structures of the model complexes formed in the reaction between hemin and peptides in solution are presented.
公益社団法人日本薬学会の論文
1979-12-25