A Pathway of Chitosan Formation in Mucor rouxii

Abstract

1 An enzyme that catalyzes hydrolysis of acetamido groups of chitin derivatives was found in the supernatant fraction of Mucor rouxii. 2 Partially O-hydroxyethylated chitin (glycol chitin) was used as a substrate in the purification and characterization of this enzyme. A 140-fold purification was obtained by means of ammonium sulfate fractionation followed by chromatography on carboxymethylcellulose and DEAE-cellulose. 3 The enzyme releases about 30% of the acetyl groups of glycol chitin, giving a product with a decreased sensitivity to lysozyme. The enzyme also deacetylates chitin and N-acetylchitooligoses, whereas it is inactive toward bacterial cell wall peptidoglycan, N-acetylated heparin, a polymer of N-acetylgalactosamine, di-N-acetylchitobiose and monomeric N-acetylglucosamine derivatives. 4 This enzyme shows a pH optimum of 5.5. The K_m value for glycol chitin is 0.87 g/l or 2.6 mM with respect to monosaccharide residues. 5 The occurrence of this enzyme accounts for the formation of chitosan in fungi.