Purification and characterization of chitinase isozymes from a red algae, Chondrus verrucosus

Three seaweed chitinase isozymes (Chi-A, B, and C) were purified from a red algae, Chondrus verrucosus. The molecular weights and isoelectric points were 24.5 kDa and 3.5 for Chi-A, 25.5 kDa and 4.6 for Chi-B, and 24.5 kDa and <3.5 for Chi-C. Optimum pH and temperature were observed at pH 2.0 at 80 degrees C for Chi-A and Chi-C, and at pH 1.0 and 70 degrees C for Chi-B. Toward N-acetylchitooligosaccharide (GlcNAc(n)) (n=2 to 6), Chi-A, B, and C hydrolyzed GlcNAc(5) and GlcNAc(6) and produced GlcNAc(n) (n=2 to 4). GlcNAc(n) (n=3, 4) with the reducing end-side of beta anomer was detected in the hydrolysis products. These results indicate that the reactions of Chi-A, B, and C for GlcNAc(n) were a retaining mechanism similar to that of family 18 chitinase. Toward crystalline chitins, Chi-A, B, and C degraded squid pen beta-chitin more than crab shell or shrimp shell alpha-chitin.