fulltext.study @t Gmail

A single point mutation enhances hydroxynitrile synthesis by halohydrin dehalogenase

Paper ID Volume ID Publish Year Pages File Format Full-Text
17049 42636 2015 8 PDF Available
Title
A single point mutation enhances hydroxynitrile synthesis by halohydrin dehalogenase
Abstract

•Halohydrin dehalogenase catalyzes epoxide-ring opening with cyanide.•A single point mutation increases the rate of β-hydroxynitrile synthesis.•Crystal structures indicate that proton transfer to the epoxide is accelerated.

The cyanide-mediated ring opening of epoxides catalyzed by halohydrin dehalogenases yields β-hydroxynitriles that are of high interest for synthetic chemistry. The best studied halohydrin dehalogenase to date is the enzyme from Agrobacterium radiobacter, but this enzyme (HheC) exhibits only low cyanolysis activities. Sequence comparison between a pair of related halohydrin dehalogenases from Corynebacterium and Mycobacterium suggested that substitution of a threonine that interacts with the active site might be responsible for the higher cyanolytic activity of the former enzyme. Here we report that a variant of HheC in which this substitution (T134A) is adopted displays an up to 11-fold higher activity in cyanide-mediated epoxide ring-opening. The mutation causes removal of the hydrogen bond between residue 134 and the side chain O of the active site serine 132, which donates a hydrogen bond to the substrate oxygen. The mutation also increases dehalogenase rates with various substrates. Structural analysis revealed that the anion-binding site of the mutant enzyme remained unaltered, showing that the enhanced activity is due to altered interactions with the substrate oxygen rather than changes in the nucleophile binding site.

Keywords
Halohydrin dehalogenase; Epoxides; Protein engineering; Ligand binding; Cyanide; Hydroxynitrile
First Page Preview
A single point mutation enhances hydroxynitrile synthesis by halohydrin dehalogenase
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 70, March 2015, Pages 50–57
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