Characterization of Trichoderma reesei Endoglucanase II Expressed Heterologously in Pichia pastoris for Better Biofinishing and Biostoning
Sutanu Samanta1,2*, Asitava Basu1, Umesh Chandra Halder3, and Soumitra Kumar Sen1
1Advanced Laboratory for Plant Genetic Engineering, Indian Institute of Technology, Kharagpur, 721302, India, 2Department of Biotechnology, Lovely Professional University, Phagwara, Punjab144401, India, 3Department of Chemistry, Jadavpur University, Kolkata 700032, India
Journal of Microbiology, 50(3),518-525, 2012,
endoglucanase, hyperglycosylation, methanol inducible promoter, Trichoderma reesei, thermostability
The endoglucanase II of Trichoderma reesei is considered the most effective enzyme for biofinishing cotton fabrics and biostoning denim garments. However, the commercially available preparation of endoglucanase II is usually mixed with other cellulase components, especially endoglucanase I, resulting in hydrolysis and weight loss of garments during biofinishing and biostoning. We thus isolated the endoglucanase II gene from T. reesei to express this in Pichia pastoris, under the control of a methanol-inducible AOX1 promoter, to avoid the presence of other cellulase components. A highly expressible Mut+ transformant was selected and its expression in BMMH medium was found most suitable for the production of large amounts of the recombinant protein. Recombinant endoglucanase II was purified to electrophoretic homogeneity, and functionally characterized by activity staining. The specific activity of recombinant endoglucanase II was found to be 220.57 EU/mg of protein. Purified recombinant endoglucanase II was estimated to have a molecular mass of 52.8 kDa. The increase in molecular mass was likely due to hyperglycosylation. Hyperglycosylation of recombinant endoglucanase II secreted by P. pastoris did not change the temperature or pH optima as compared to the native protein, but did result in increased thermostability. Kinetic analysis showed that recombinant endoglucanase was most active against amorphous cellulose, such as carboxymethyl cellulose, for which it also had a high affinity.