Chitinase Chi1 of Aeromonas caviae CB101 possesses chitin binding sites at both its N and C termini. Four putative exposed residues aligned in a line on the surface of the N-terminal domains of Chi1 were found to contribute to the enzyme-chitin binding and hydrolysis via site-directed mutagenesis. Also, it was found that Chi1 requires the cooperation of the N- and C-terminal domains to bind fully with crystalline and colloidal chitin.