Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 343325
Title Increasing the transglycosylation activity of alpha-galactosidase from Bifidobacterium adolescentis DSM 20083 by site-directed mutagenesis
Author(s) Hinz, S.W.A.; Doeswijk-Voragen, C.H.L.; Schipperus, R.; Broek, L.A.M. van den; Vincken, J.P.; Voragen, A.G.J.
Source Biotechnology and Bioengineering 93 (2006)1. - ISSN 0006-3592 - p. 122 - 131.
Department(s) Food Chemistry Group
WU Agrotechnology and Food SciencesDepartment of Agrotechnology and Food Sciences
Bioprocess Engineering
Publication type Refereed Article in a scientific journal
Publication year 2006
Keyword(s) beta-glucosidase - pyrococcus-furiosus - crystal-structure - chain elongation - dsm 20083 - oligosaccharides - raffinose - amylase - hydrolysis - resolution
Abstract The ¿-galactosidase (AGA) from Bifidobacterium adolescentis DSM 20083 has a high transglycosylation activity. The optimal conditions for this activity are pH 8, and 37°C. At high melibiose concentration (600 mM), approximately 64% of the enzyme-substrate encounters resulted in transglycosylation. Examination of the acceptor specificity showed that AGA required a hydroxyl group at C-6 for transglycosylation. Pentoses, hexuronic acids, deoxyhexoses, and alditols did not serve as acceptor molecules. Disaccharides were found to be good acceptors. A putative 30-structure of the catalytic site of AGA was obtained by homology modeling. Based on this structure and amino acid sequence alignments, site-directed mutagenesis was performed to increase the transglycosylation efficiency of the enzyme, which resulted in four positive mutants. The positive single mutations were combined, resulting in six double mutants. The mutant H497M had an increase in transglycosylation of 16%, whereas most of the single mutations showed an increase of 2%-5% compared to the wild-type AGA. The double mutants G382C-Y500L, and H497M-Y500L had an increase in transglycosylation activity of 10%-16%, compared to the wild-type enzyme, whereas the increase for the other double mutants was low (4%-7%). The results show that with a single mutation (H497M) the transglycosylation efficiency can be increased from 64% to 75% of all enzyme-substrate encounters. Combining successful single mutants in double mutations did not necessarily result in an extra increase in transglycosylation efficiency. The donor and acceptor specificity did not change in the mutants, whereas the thermostability of the mutants with G382C decreased drastically
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