PURIFICATION AND PROPERTIES OF 2 ENDOCHITOSANASES FROM MUCOR-ROUXII IMPLICATED IN ITS CELL-WALL DEGRADATION

From autolysed cultures of Mucor rouxii, two chitosanases, A and B, were purified to electrophoretic homogeneity. Apparent M(r) values of 76000 and 58000 and pI values of 4.9 and 4.7 were determined for A and B, respectively. Both chitosanases showed a high specificity for chitosan and chitosan derivatives. They had optimum activities at pH 5.0 and at temperatures of 55-degrees-C and 50-degrees-C for A and B, respectively. Enzyme A was inhibited by acetate ions and enzyme B by high substrate concentration. Both enzymes showed an endo-splitting type of activity, and the end product of chitosan degradation contained a mixture of dimer, trimer and higher molecular mass oligomers of glucosamine. Glucosamine oligosaccharides were poorly hydrolysed by these enzymes. Both enzymes extensively degraded the chitosan extracted from M. rouxii cell walls.