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Cu B promotes both binding and reduction of dioxygen at the heme‐copper binuclear center in the Escherichia coli bo ‐type ubiquinol oxidase
Author(s) -
Tatsushi Mogi,
Toshisuke Hirano,
H. Nakamura,
Yasuhiro Anraku,
Yutaka Orii
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00852-z
Subject(s) - chemistry , ubiquinol , oxidase test , heme , myoglobin , escherichia coli , ligand (biochemistry) , photochemistry , stereochemistry , copper , oxygen , mutant , enzyme , biochemistry , cytochrome c , coenzyme q – cytochrome c reductase , mitochondrion , organic chemistry , receptor , gene
A Cu B ‐deficient mutant of the Escherichia coli bo ‐type ubiquinol oxidase exhibits a very low oxidase activity that is consistent with a decreased dioxygen binding rate. During the turnover, a photolabile reaction intermediate persists for a few hundred milliseconds, due to much slower heme o ‐to‐ligand electron transfer. Thus, the lack of Cu B seems to have endowed the mutant enzyme with myoglobin‐like properties, thereby stabilizing the CO‐bound form, too. Accordingly we conclude that Cu B plays a pivotal role in preferential trapping and efficient reduction of dioxygen at the heme‐copper binuclear center.