Non-structured amino-acid impact on GH11 differs from GH10 xylanase.

ABSTRACT: The Aspergillus niger xylanase (Xyn) was used as a model to investigate impacts of un-structured residues on GH11 family enzyme, because the ?-jelly roll structure has five residues (Ser1Ala2Gly3Ile4Asn5) at N-terminus and two residues (Ser183Ser184) at C-terminus that do not form to helix or strand. The N- or/and C-terminal residues were respectively deleted to construct three mutants. The optimal temperatures of Xyn?N, Xyn?C, and Xyn?NC were 46, 50, and 46°C, and the thermostabilities were 15.7, 73.9, 15.5 min at 50°C, respectively, compared to 48°C and 33.9 min for the Xyn. After kinetic analysis, the substrate-binding affinities for birch-wood xylan decreased in the order Xyn?C>Xyn>Xyn?NC>Xyn?N, while the K(cat) values increased in the order Xyn?C

SUBMITTER: Liu L 

PROVIDER: S-EPMC3448673 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature