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Structure–function relationship in cyclodextrin glycosyltransferase from Bacillus circulans DF 9R
Cyclodextrin glycosyltransferases catalyze cyclodextrin production allowing major industrial applications. This work is a contribution to the knowledge of structural and functional aspects of these enzymes, special emphasis being cast on product specificity; besides, a single modification in the hig...
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Published in: | Carbohydrate research 2009-01, Vol.344 (1), p.74-79 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Cyclodextrin glycosyltransferases catalyze cyclodextrin production allowing major industrial applications. This work is a contribution to the knowledge of structural and functional aspects of these enzymes, special emphasis being cast on product specificity; besides, a single modification in the highly conserved −6 subsite—involved in the induced-fit mechanism—was found.
Cyclodextrin glycosyltransferases (CGTases E.C.2.4.1.19) catalyze cyclomaltooligosaccharides (cyclodextrins) production, an important industrial process. We herein report structural features of
Bacillus circulans DF 9R cyclodextrin glycosyltransferase including its sequence and several aspects of enzyme structure–function relationship. Protein ethoxyformylation, under our experimental conditions, indicated that only one out of the 13 enzyme histidines was modified leading to a drastic drop in cyclizing and hydrolytic activity. Besides, tryptic digestion of the
14C ethoxyformylated protein and studies of the peptide mixture showed that histidine 233 is the most reactive histidine residue. This is the first cyclodextrin glycosyltransferase with a known primary structure and a glutamine instead of glycine residue at position 179 in the highly conserved −6 subsite, shown to be involved in substrate binding. The presence of glycine at that position was considered as a requirement for such binding following the induced-fit mechanism already proposed. Moreover, the enzyme has all the features previously described for an α- or α/β-cyclodextrin producer. |
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ISSN: | 0008-6215 1873-426X |
DOI: | 10.1016/j.carres.2008.09.023 |