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Improved activity of ?-cyclodextrin glycosyltransferase from Bacillus sp. N-227 via mutagenesis of the conserved residues.

ABSTRACT: ?-Cyclodextrin glycosyltransferase (?-CGTase) belongs to the ?-amylase family of enzymes and converts starch to cyclic oligosaccharides called ?-cyclodextrins (?-CD). The ?-CGTase from alkalophilic Bacillus sp. N-227 was separately mutagenized to give three site-directed ?-CGTase mutants, Y127F, R254F and D355R, that showed enhanced cyclization activity towards a starch substrate from 1.64 to 2.1-folds. Kinetic studies indicate that the mutants had higher affinity towards the substrate than the wild type ?-CGTase. The Y127F mutant had the highest affinity which was indicated by the lowest K m of 15.30 mM and the highest catalytic activity. Increasing hydrophobicity around the catalytic center appeared to favor the cyclization activity of the mutants. The ?-CGTase and the three mutants showed optimal enzyme activity at 60 °C and pH 6.0. All the enzymes were stable for at least 60 min across a wide pH range (5.0-7.0).

SUBMITTER: Wang H

PROVIDER: S-EPMC5465042 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Improved activity of β-cyclodextrin glycosyltransferase from Bacillus sp. N-227 via mutagenesis of the conserved residues.

Wang Hua H Zhou Wenxi W Li Hua H Rie Bu B Piao Chunhong C

3 Biotech 20170608 2

β-Cyclodextrin glycosyltransferase (β-CGTase) belongs to the α-amylase family of enzymes and converts starch to cyclic oligosaccharides called β-cyclodextrins (β-CD). The β-CGTase from alkalophilic Bacillus sp. N-227 was separately mutagenized to give three site-directed β-CGTase mutants, Y127F, R254F and D355R, that showed enhanced cyclization activity towards a starch substrate from 1.64 to 2.1-folds. Kinetic studies indicate that the mutants had higher affinity towards the substrate than the ...[more]

PMID: 28597161

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