Abstract
Chitinases Al and D were purified from the periplasmic proteins produced by Escherichia coli HB101 harbouring recombinant plasmids carrying respectively the chiA and chiD genes of Bacillus circulans WL-12. HPLC analysis indicated that during the hydrolysis of chitotriose, both chitinases initially produce N-acetylglucosamine and only one anomer of chitobiose. H-1 NMR spectroscopy of the hydrolysis of chitotetraitol showed that this anomer corresponds to beta-chitobiose, demonstrating that chitinases Al and D act by a molecular mechanism that retains the anomeric configuration. This mechanism is similar to that of lysozymes although both chitinases belong to a family of proteins sharing no demonstrable amino acid sequence similarity with lysozymes.