Abstract: Water-soluble chitosan with low molecular weight was employed to modify polygalacturonase (PG). After modification, the catalytic kinetics of PG and modified polygalacturonase (COS-PG) were investigated in buffer, methanol, ethanol, acetone and tetrahydrofuran solution using pectin as substrate. The results indicated that Km of COS-PG revealed a slight decline, but Vmax revealed an increase. Km and Vmax of PG and COS-PG declined both in 2% methanol and 2% ethanol. Km  and Vmax  of PG and COS-PG increased in 2% tetrahydrofuran solution. Conversely, in 2% acetone solution, Km  increased but Vmax  declined.

Key words: polygalacturonase, organic solvents, dynamics