Enzyme of use in chitosan hydrolysis

A chitosanase isolated from Streptomyces N174 or obtained from a microorganism of the genus Streptomyces which produces said chitosanase, the chitosanase hydrolysing specifically a substrate chitosan, said chitosanase having the following characteristics:

• an apparent molecular weight (M.sub.r) of 29500 kilodaltons measured by SDS-polyacrylamide gel electrophoresis;
• a pH range for activity extending from 4.0 to 6.0, with a maximum of activity at pH 5.5;
• an apparent constant of affinity (k.sub.m) for said substrate chitosan of 0.088 mg/ml and a maximal velocity of hydrolysis (V.sub.max) of 96.6 U/mg, where in U is defined as the amount of chitosanase that liberates 1 .mu.mol of the product of said hydrolysis, D-glucosamine equivalent, in one minute of enzymatic reaction at 37.degree. C. in a one ml volume of reaction containing 50 mM acetate buffer pH 5.5 and 0.2% solubilized chitosan having a degree of acetylation of 21%, the reaction of said substrate with said chitosanase being allowed for 10 minutes and stopped by addition of neocuproine reagent.