Selective Monoacylation of Diols by Substrate Assisted Catalysis in T40A Candida antarctica Lipase B

Authors

  • Dr. Anders Hamberg,

    1. Division of Biochemistry, KTH School of Biotechnology, KTH, AlbaNova University Centre, Division of Biochemistry, SE-106 91 Stockholm (Sweden), Fax: (+46) 8-5537-8468
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  • Dr. Anders O. Magnusson,

    1. Division of Biochemistry, KTH School of Biotechnology, KTH, AlbaNova University Centre, Division of Biochemistry, SE-106 91 Stockholm (Sweden), Fax: (+46) 8-5537-8468
    2. Present address: DECHEMA-Forschungsinstitut, Biochemical Engineering, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main (Germany)
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  • Francis J. Hu,

    1. Division of Biochemistry, KTH School of Biotechnology, KTH, AlbaNova University Centre, Division of Biochemistry, SE-106 91 Stockholm (Sweden), Fax: (+46) 8-5537-8468
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  • Prof. Karl Hult

    Corresponding author
    1. Division of Biochemistry, KTH School of Biotechnology, KTH, AlbaNova University Centre, Division of Biochemistry, SE-106 91 Stockholm (Sweden), Fax: (+46) 8-5537-8468
    • Division of Biochemistry, KTH School of Biotechnology, KTH, AlbaNova University Centre, Division of Biochemistry, SE-106 91 Stockholm (Sweden), Fax: (+46) 8-5537-8468
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Abstract

The selectivity towards diols over monoesters in the esterification of diols catalysed by lipase B from Candida antarctica (CALB) was improved by the single point mutation T40A in the enzyme’s oxyanion hole. Substrate-assisted catalysis was suggested from molecular modelling of the tetrahedral intermediate in esterification of 1,2-ethanediol catalysed by T40A CALB. The non-reacting hydroxyl group of the diol forms a hydrogen bond to the oxyanion in the transition state, replacing that deleted in mutation. Monoester yields in transacylation reactions were monitored over time to compare the selectivities for wild-type and T40A CALB. The results showed increased selectivities towards the diols tested over their corresponding monoesters as a result of the T40A mutation with substrate-assisted catalysis as a plausible explanation.

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