title: Emulation of racemase activity by employing a pair of stereocomplementary biocatalysts.
abstract: Racemization is the key step to turn a kinetic resolution process into dynamic resolution. A general strategy for racemization under mild reaction conditions by employing stereoselective biocatalysts is presented, in which racemization is achieved by employing a pair of stereocomplementary biocatalysts that reversibly interconvert an sp3 to a sp2 center. The formal interconversion of the enantiomers proceeds via a prochiral sp2 intermediate the formation of which is catalyzed either by two stereocomplementary enzymes or by a single enzyme with low stereoselectivity. By choosing appropriate reaction conditions, the amount of the prochiral intermediate is kept to a minimum. This general strategy, which is applicable to redox enzymes (e.g., by acting on R2CHOH and R2CHNHR groups) and lyase-catalyzed addition-elimination reactions, was proven for the racemization of secondary alcohols by employing alcohol dehydrogenases. Thus, enantiopure chiral alcohols were used as model substrates and were racemized either with highly stereoselective biocatalysts or by using (rarely found) non-selective enzymes.
authors.affiliation: Department of Chemistry, Organic and Bioorganic Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Gruber
authors.forename: Bettina M
authors.initials: BM
authors.lastname: Nestl
authors.forename: Johannes
authors.initials: J
authors.lastname: Gross
authors.forename: Petra
authors.initials: P
authors.lastname: Hildebrandt
authors.forename: Uwe T
authors.initials: UT
authors.lastname: Bornscheuer
authors.forename: Kurt
authors.initials: K
authors.lastname: Faber
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kroutil
mesh_terms: D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D000438:Alcohols / Q000737:chemistry; D001419:Bacteria / Q000201:enzymology; D001711:Biotransformation; D002384:Catalysis; D019998:Racemases and Epimerases / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D000438:Alcohols; D000426:Alcohol Dehydrogenase; D019998:Racemases and Epimerases