Chitosanase, a Novel Enzyme

Abstract

CHITIN is a structural polysaccharide composed of β(1→4) linked N-acetyl-D-glucosamine residues, found widely in exoskeletons of animals and in cell walls of green algae and fungi^1,2. Chitosan is a partially deacetylated form of chitin²; those commercially available have an average degree of acetylation of 10–30% and are prepared by treating chitin with concentrated alkali at high temperature. Chitosan also occurs naturally in different degrees of acetylation, often in close association with chitin. A mainly deacetylated form is a major component of the zygomycete fungal cell wall³ while chitins showing a 10% deacetylated but poorly defined fraction have also been found in squid pen, lobster, crab and Rhodnius^4,5. The chitosan complex is probably a widely occurring structural polymer. Other modifications of the chitin polymer exist as essential components of bacterial cell walls. In some bacteria, alternate N-acetylglucosamine units are substituted at C3 (peptidoglycan), and these are susceptible to lysozyme; in others, a modification occurs in which many of the NAc glucosamine units have lost their acetyl groups. Egg white lysozyme will not attack this naturally occurring de-N-acetylated mucopeptide⁶.