Reactivities of oxo and peroxo intermediates studied by hemoprotein mutants.
A series of myoglobin mutants, in which distal sites are modified by site-directed mutagenesis, are able to catalyze peroxidase, catalase, and P450 reactions even though their proximal histidine ligands are intact. More importantly, reactions of P450, catalase, and peroxidase substrates and compound I of myoglobin mutants can be observed spectroscopically. Thus, detailed oxidation mechanisms were examined. On the basis of these results, we suggest that the different reactivities of P450, catalase, and peroxidase are mainly caused by their active site structures, but not the axial ligand. We have also prepared compound 0 under physiological conditions by employing a mutant of cytochrome c 552. Compound 0 is not able to oxidize ascorbic acid.
Watanabe
Yoshihito
Y
Research Center for Materials Science and Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
Nakajima
Hiroshi
H
Ueno
Takafumi
T
D001205:Ascorbic Acid / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002374:Catalase / Q000737:chemistry; D018360:Crystallography, X-Ray; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry* / Q000235:genetics; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009211:Myoglobin / Q000737:chemistry* / Q000235:genetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D009195:Peroxidase / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013329:Structure-Activity Relationship
D003574:Cytochrome c Group; D008024:Ligands; D009211:Myoglobin; D003577:Cytochrome P-450 Enzyme System; C022302:cytochrome C-552; D010088:Oxidoreductases; D002374:Catalase; D009195:Peroxidase; D001205:Ascorbic Acid