Goeger D E, Ganther H E
Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston 77555-1009.
Arch Biochem Biophys. 1994 May 1;310(2):448-51. doi: 10.1006/abbi.1994.1191.
Oxidation of [75Se]dimethylselenide by rat liver and lung microsomes and by purified flavin-containing monooxygenase from pig liver was demonstrated. Quantitation of the nonvolatile product showed a 1:1 stoichiometry with NADPH oxidation, consistent with selenoxide formation. The apparent Km for dimethylselenide was 0.7 microM with rat liver microsomes and 0.3 microM with purified pig liver enzyme. Facile reversal of dimethylselenide oxidation by reducing agents present in microsomes, and by glutathione, indicates that redox cycling can occur. Unlabeled dimethylselenoxide carrier circumvented reduction of the labeled product, permitting quantitation. This is the first demonstration of a naturally occurring selenium substrate for the microsomal flavin-containing monooxygenase.
已证实大鼠肝脏和肺微粒体以及猪肝纯化的含黄素单加氧酶可氧化[75Se]二甲基硒化物。对非挥发性产物的定量分析表明，其与NADPH氧化的化学计量比为1:1，这与亚硒氧化物的形成一致。大鼠肝脏微粒体中二甲基硒化物的表观Km为0.7 microM，猪肝纯化酶的表观Km为0.3 microM。微粒体中存在的还原剂以及谷胱甘肽可轻易逆转二甲基硒化物的氧化，这表明可能发生氧化还原循环。未标记的二甲基亚硒氧化物载体可避免标记产物的还原，从而实现定量分析。这是首次证明微粒体含黄素单加氧酶存在天然硒底物。
