关键词: 甘露聚糖酶；嗜热微生物；Achaetomium sp.；热稳定性；生物信息学

Abstract:

The consistency of amino acid sequence of two reported GH5 mannase, Man5Xz8 from the thermophilic fungi Achaetomium sp. Xz8 and Man5A from Humicola sp. Y1, was as high as 90.0%. However, their enzymology properties, especially their optimum temperature and thermal stability were different. Man5A had the temperature optima of 70℃ and possessed pretty good thermal stability under 50℃, while  Man5Xz8 had the temperature optima of 50℃ and only could stay good thermal stability at 30℃. The mutants V124I and △SG were built based on the analysis of bioinformatics methods. The results showed that the mutants had similar optimal pH and temperature with Man5Xz8, while their thermal stabilities were much betten than Man5Xz8. After treated at 50 ℃ for 10 min, the thermal stability of V124I was greatly increased when compared with their wild-type Man5Xz8 and the residual enzyme activity was increased by 26.9%. Moreover, the mutant △SG can stay good thermal stability at 50℃ for 1 h. Through the study of different amino acid sites of Man5Xz8, some key factors of the thermal stability were found, which provided certain theoretical guidance for the better research of GH5 famliy mannases.

Key words: mannase, thermophilic microorganisms, Achaetomium sp., thermal stability, bioinformatics