生体防御系のヘムタンパク質
食細胞のb型シトクロームによるスーパーオキシド生成機構の解析
1994 年 34 巻 3 号 p. 117-123
詳細
1994 年 34 巻 3 号 p. 117-123
Phagocytic cytochrome b558 is a membrane-bound heme-containing enzyme that catalyzes one-electron reduction of O2 to produce superoxide anion. This cytochrome b has a low-spin 6-coordinate heme iron, and its catalytic activity is not inhibited by respiratory inhibitors such as CO. In this paper, the recent progress is reviewed focusing on the structure and the function of the cytochrome. Our spectroscopic and kinetic data suggest that cytochrome b558 catalyzes the O2- production without ligation of O2 to the heme iron during the catalytic cycle. The mechanisms of oxygen reduction and regulation of the electron transfer reactions are discussed.
