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Enhancement of α-cyclodextrin product specificity by enriching histidines of α-cyclodextrin glucanotransferase at remote subsite −6

Paper ID Volume ID Publish Year Pages File Format Full-Text
34787 45048 2014 7 PDF Available
Title
Enhancement of α-cyclodextrin product specificity by enriching histidines of α-cyclodextrin glucanotransferase at remote subsite −6
Abstract

•We improve product specificity by inserting histidine residues in the active groove.•The histidine-rich mutant obtains the high α:β ratio of 13.2.•The mutant has good ability to convert raw starch.•The mutant can have better potential in industrial application as biocatalysts.

The industrial use of α-cyclodextrins (α-CDs) has increased because their solubility is higher than those of β-CDs. However, improving the product specificity of α-cyclodextrin glucanotransferases (CGTases) remains unresolved. In this study, three mutants (Y167-deletion, Y167HH, and Y167HHH) were constructed at subsite −6 of α-CGTase to investigate the contribution of amino acid residue 167 to the cyclization ability of α-CD by comparing it with Tyr167His mutant α-CGTase (previously constructed based on the wild-type gene of Bacillus sp. 602-1). As expected, the α:β ratio improved with increasing number of histidine along with residue 167. The Y167HHH mutant had the highest α:β ratio of 13.2 and almost produced single type α-CDs. The Y167HHH mutant enzyme was subsequently purified to homogeneity. The enzymatic properties and the optimal condition of Y167HHH mutant in converting raw starch were also investigated. This study discusses product specificity improvement by inserting specific amino acid residues in the active groove. The results indicate that the histidine-rich mutant α-CGTase possessed better potential in producing α-CDs in an industrial scale.

Keywords
α-Cyclodextrin glucanotransferases; α-Cyclodextrin; Product specificity; Site-directed mutagenesis; Enzymatic properties
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Enhancement of α-cyclodextrin product specificity by enriching histidines of α-cyclodextrin glucanotransferase at remote subsite −6
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 49, Issue 2, February 2014, Pages 230–236
Authors
, , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us