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The isomerization catalyzed by Brevibacterium sterolicum cholesterol oxidase proceeds stereospecifically with one
1Department of Chemistry, State University of New York at Stony Brook 11794-3400.
Biochemical and Biophysical Research Communications
|January 17, 1995
Abstract:
We have demonstrated that the isomerization reaction catalyzed by Brevibacterium sterolicum (ATCC 81387) cholesterol oxidase (EC 1.1.3.6) proceeds via a stereospecific proton transfer from the 4 beta carbon to the 6 beta carbon to form 4-cholestene-3-one using deuterated and nondueterated substrates. This result implies that there is one active site base, positioned over the beta-face, responsible for isomerization. On the basis of X-ray crystallographic evidence [Li, J., Vrielink, A., Brick, P. & Blow, D. M. Biochemistry 32, 11507-11515 (1993)], glutamate-361 is the most likely candidate for this general base.