Enhancement of thermostability of GH10 xylanase E Penicillium canescens directed by ΔΔG calculations and structure analysis.

Hydrolytic enzymes are highly demanded in the industry. Thermostability is an important property of enzymes that affects the economic costs of the industrial processes. The rational design of GH10 xylanase E (XylE) Penicillium canescens for the thermostability improvement was directed by ΔΔG calculations and structure analysis. Amino acid substitutions with stabilizing values of ΔΔG and providing an increase in side-chain volume of buried residues were performed experimentally. From the six designed substitutions, four substitutions appeared to be stabilizing, one - destabilizing, and one - neutral. For the improved XylE variants, values of T were increased by 1.1-3.1 °C, and times of half-life at 70 °C were increased in 1.3-1.7-times. Three of the four stabilizing substitutions were located in the N- or the C-terminus region. This highlights the importance of N- and C-terminus for the thermostability of GH10 xylanases and also enzymes with (β/α) TIM barrel type of structure. The criteria of stabilizing values of ΔΔG and increased side-chain volume of buried residues for selection of substitutions may be applied in the rational design for thermostability improvement.