thermal stability of cryptococcus sp. s-2 carboxymethyl cellulase (cscmcase) having a cellulose binding domain from a fungal exoglucanase: comparison to recombinant cscmcase

The Cryptococcus sp. S-2 carboxymethyl cellulase gene (CSCMCase) containing 1023 nucleotides and fused to acellulose-binding domain (CBD) which originated from cellobiohydrolase I of Trichoderma reesei (CSCMCase-CBD) wascloned and expressed in the methylotrophic yeast, Pichia pastoris. The fusion of CBD to CSCMCase resulted in a greatlyenhanced binding toward cellulose for CSCMCase-CBD compared with that for CSCMCase. This was useful for enzymepurification and enzyme immobilization. Furthermore, the recombinant CSCMCase-CBD showed high thermal stability afterincubating at 90oC for 3 h, whereas the recombinant CSCMCase rapidly lost its activity after incubating at 90oC for 1 h.