Functional characterisation of cellobiohydrolase I (Cbh1) from Trichoderma virens UKM1 expressed in Aspergillus niger.

摘要: Abstract Cellobiohydrolases catalyze the processive hydrolysis of cellulose into cellobiose. Here, a Trichoderma virens cDNA predicted to encode for cellobiohydrolase (cbhI) was cloned and expressed heterologously in Aspergillus niger. The cbhI gene has an open reading frame 1518 bp, encoding putative protein 505 amino acid residues with calculated molecular mass approximately 54 kDa. CbhI sequence fungal type carbohydrate binding module separated from catalytic domain by threonine rich linker region showed high homology glycoside hydrolase family 7 proteins. partially purified enzyme optimum pH 4.0 stability ranging 3.0 6.0 temperature 60 °C. specific activity 4.195 Umg−1 low Km value 1.88 mM when p-nitrophenyl-β-D-cellobioside (pNPC) is used as substrate. efficiency (kcat/Km) 5.68 × 10−4 mM−1s−1, which comparable enzymes viridae Phanaerochaete chrysosporium. also towards complex substrates such Avicel (0.011 Umg−1), could be useful biomass degradation. Interestingly, exhibited relatively inhibition constant (Ki) cellobiose 8.65 mM, making this more resistant end-product compared other cellobiohydrolases.