The isomerization catalyzed by Brevibacterium sterolicum cholesterol oxidase proceeds stereospecifically with one base.
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.
Kass
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IJ
Department of Chemistry, State University of New York at Stony Brook 11794-3400.
Sampson
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NS
D001951:Brevibacterium / Q000201:enzymology*; D002783:Cholestenones / Q000737:chemistry / Q000378:metabolism; D002789:Cholesterol Oxidase / Q000378:metabolism*; D007536:Isomerism; D008968:Molecular Conformation; D015394:Molecular Structure; D013237:Stereoisomerism
D002783:Cholestenones; D002789:Cholesterol Oxidase