Stabilization of xylanase by random mutagenesis

Abstract
Four heat‐resistant mutants of xylanase (N56, N102, N104 and F1) were obtained by random mutagenesis. The mutant genes had the following amino acid changes: N56, Ser‐26 to Trp, Gly‐38 to Asp and Thr‐126 to Ser; N102, Gly‐38 to Asp; N104, Gly‐38 to Ser and Arg‐48 to Lys; F1, Ser‐12 to Cys. Kinetic studies showed that N104 is stabilized by an increase in the activation enthalpy, while the other mutants are stabilized by a decrease in the activation entropy.