Expression and characterization of two secreted His6-tagged endo-β-1,4-glucanases from the mollusc Ampullaria crossean in Pichia pastoris
Authors: Guo, Rui1; Ding, Ming2; Zhang, Siliang1; Xu, Genjun; Zhao, Fukun
Source: Acta Biochimica et Biophysica Sinica, Volume 40, Number 5, May 2008 , pp. 419-425(7)
Publisher: Blackwell Publishing
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Abstract:
Two endo-β-1,4-glucanase cDNAs, eg27I and eg27II, from the mollusc Ampullaria crossean were expressed in Pichia pastoris cells. The secreted His6-tagged proteins were purified in a single chromatography step. The purified recombinant EG27I and EG27II showed enzymatic activity on carboxylmethyl cellulose sodium salt at 15.31 U/mg and 12.40 U/mg, respectively. The optimum pH levels of the recombinant EG27I and EG27II were 5.5 and 5.5-6.0, respectively, and the optimum temperatures were 50°C and 50°C-55°C, respectively. The pH stability study revealed that both EG27I and EG27II showed their highest stability at pH 8.0. Analysis of their thermostability indicated that both EG27I and EG27II were relatively stable up to 40°C. Site-directed mutagenesis of Asp43 and Asp153 of both EG27I and EG27II showed that the two Asp residues are critical for the enzymatic activity.Keywords: cellulase; endoglucanase; EG27I; EG27II; Ampullaria crossean; Pichia pastoris
Document Type: Research article
DOI: 10.1111/j.1745-7270.2008.00413.x
Affiliations: 1: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China 2: Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 20031, China
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