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Kinetics and substrate selectivity of a Triticum aestivum xylanase inhibitor (TAXI) resistant D11F/R122D variant of Bacillus subtilis XynA xylanase

Paper ID Volume ID Publish Year Pages File Format Full-Text
24391 43511 2010 8 PDF Available
Title
Kinetics and substrate selectivity of a Triticum aestivum xylanase inhibitor (TAXI) resistant D11F/R122D variant of Bacillus subtilis XynA xylanase
Abstract

This study examined the kinetics and substrate selectivity of a GH11 Bacillus subtilis XynA xylanase (BsX) sensitive to inhibition by TAXI and an engineered variant, which is much less inhibited by TAXI (BsXmut). The main purpose of the work was to elucidate any influence of the structural point mutations on the kinetics and substrate selectivity of the enzyme. Three-dimensional structures of both xylanases were superimposed to elucidate the structural basis for differences in their hydrolytic properties. The two xylanases were incubated individually with water-extractable arabinoxylan (WEAX), water-unextractable arabinoxylan (WUAX), birchwood xylan, and wheat bran. Both the BsX and the BsXmut catalyzed the release of xylo-oligosaccharides with higher degree of polymerization from WUAX than from WEAX. At equimolar addition levels the activity of the BsXmut was lower than that of the BsX with respect to both the initial rate and the product yields obtained after prolonged reaction on the xylan substrates. The calculated substrate selectivity factors indicated that the BsX and the BsXmut both had higher catalytic rate on WUAX than on WEAX. Addition of a 100:1 (TAXI:xylanase) molar ratio of inhibitor confirmed the significantly decreased inhibition of BsXmut by TAXI. Addition of TAXI also influenced the xylanases’ selectivity factor differently.

Keywords
Endoxylanase; Arabinoxylan; Inhibition; TAXI; Selectivity; Xylo-oligosaccharide profile
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Kinetics and substrate selectivity of a Triticum aestivum xylanase inhibitor (TAXI) resistant D11F/R122D variant of Bacillus subtilis XynA xylanase
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 146, Issue 4, 15 April 2010, Pages 207–214
Authors
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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