| Literature DB >> 9240456 |
Abstract
The electron donors for the membrane-bound sterol-4alpha-methyl-oxidases and sterol C5(6)-desaturase of plant sterol biosynthesis have not been previously identified. The requirement of cytochrome b5 to shuttle reducing equivalents from NAD(P)H to 4,4-dimethylsterol-4alpha-methyl oxidase (4,4-DMSO), 4alpha-methylsterol-4alpha-methyl oxidase (4alpha-MSO), and delta7-sterol-C5(6) desaturase (5-DES) was investigated using a purified preparation of IgG raised against plant cytochrome b5. The activities of 4,4-DMSO, 4alpha-MSO, and 5-DES, three oxidative reactions not mediated by cytochrome P-450, were strongly and completely inhibited by the antibody in a microsomal preparation from maize. In addition the IgG also inhibited NADH-dependent cytochrome c reduction in the same preparation. These results strongly suggest that membrane-bound cytochrome b5 of maize microsomes is an obligatory electron carrier from NAD(P)H to 4,4-DMSO, 4alpha-MSO, and 5-DES.Entities:
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Year: 1997 PMID： 9240456 DOI： 10.1006/bbrc.1997.6974
Source DB: PubMed Journal: Biochem Biophys Res Commun ISSN： 0006-291X Impact factor: 3.575