Enzyme Surface Glycosylation in the Solid Phase: Improved Activity and Selectivity of Candida Antarctica Lipase B

摘要: Tailor-made oligosaccharides and polymers were investigated for a specific surface glycosylation of Candida antarctica lipase (fraction B) (CAL-B) already immobilized on octyl-Sepharose by interfacial activation. The chemical modification was performed in the N-terminal amino acid enzyme residue using low oxidized aldehyde–dextran through reductive amination. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicated that polymer/enzyme conjugates obtained all cases. Circular dichroism experiments revealed interesting conformational changes secondary tertiary structures protein after modification. formed glycosylated biocatalysts more stable, active, selective toward different substrates than unmodified CAL-B. These compared with genetically version CAL-B expressed Pichia pastoris same way. Enzyme thermostability improved Dextran-1500 also genetic glycosylation, retaining 90–96 % activity 24 h at 55 °C. catalytic incorporation dextran (Mw=1500 or 6000) twofold hydrolysis p-nitrophenylbutyrate threefold methyl mandelate pH 7. However, lower both substrates. enantioselectivity increased bioconjugates, Dextran-1500–CAL-B conjugate being most racemic (up to 88.1 % ee pH 5). This demonstrated highest synthetic transesterification butyrate glycerol, 80 % yield monoglyceryl ester 100 % conversion 57 % other polymer–lipase conjugates.