Abstract: The effects of some protein modification reagents on the activity of cyclodextrin glucanotransferase(CGTase) have been studied. That the enzyme was not affected by DIC, PMSF, DTT and Ch-T modification, suggested that guanido, hydroxyl, disulfide bond and mehionine residues were insignificant to enzyme activity. The enzyme activity was remarkably decreased after DEPC, NBS, EDC modification.The results indicated that carboxyl group, imidazolyl group and indolyl group seemed to be significant to the catalytic activity of cyclodextrin glucantransferase.

Key words: alkalophilic Bacillus sp.7-12, cyclodextrin glucantransferase, chemical modification