Direct Epoxidation in Candida antarctica Lipase B Studied by Experiment and Theory
2008 (English)In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, no 15, 2443-2451 p.Article in journal (Refereed) Published
Candida antarctica lipase B (CALB) is a promiscuous serine hydrolase that, besides its native function, catalyzes different side reactions, such as direct epoxidation. A single-point mutant of CALB demonstrated a direct epoxidation reaction mechanism for the epoxidation of alpha,beta-unsaturated aldehydes by hydrogen peroxide in aqueous and organic solution. Mutation of the catalytically active Ser105 to alanine made the previously assumed indirect epoxidation reaction mechanism impossible. Gibbs free energies, activation parameters, and substrate selectivities were determined both computationally and experimentally. The energetics and mechanism for the direct epoxidation in CALB Ser105Ala were investigated that the reaction proceeds through a two step-mechanism with formation of an oxyanionic intermediate. The active-site residue His224 functions as a general acid-base catalyst with support from Asp187. Oxyanion stabilization is facilitated by two hydrogen bonds from Thr40.
Place, publisher, year, edition, pages
2008. Vol. 9, no 15, 2443-2451 p.
catalytic promiscuity, enzyme catalysis, epoxidation, hydrolases, molecular dynamics, HYDROGEN-PEROXIDE, ACTIVE-SITE, PEROXYCARBOXYLIC ACIDS, EFFICIENT GENERATION, AM1-BCC MODEL, CATALYSIS, ALKENES, ENZYMES, OXIDATION, CHLOROPEROXIDASE
IdentifiersURN: urn:nbn:se:kth:diva-13270DOI: 10.1002/cbic.200800318ISI: 000260591100015ScopusID: 2-s2.0-54349127157OAI: oai:DiVA.org:kth-13270DiVA: diva2:323008