PROPERTIES OF CHITIN DEACETYLASE FROM CRUDE EXTRACTS OF MUCOR ROUXII MYCELIUM

The catalytic properties of chitin deacetylase from Mucor rouxii were studied with the aim of using the results for control of the properties of chitosan prepared by enzymatic deacetylation. A crude deacetylase extract from the mycelium of Mucor rouxii exhibited maximal activity at pH 5.8 with both water-soluble and acid-soluble chitosan. The extracellular enzyme of the culture medium exhibited maximal activity at pH 4.8. The deacetylase in the crude extract was stable over the pH range of 4.1-8.9 at 25C, retaining 85-100% of maximal activity at 40C. The extract was most active towards acid-soluble chitoson at 50C and pH 5.8. Chitin deacetylase was stable to 40C when incubated without substrate, with 85% of the activity retained at 50C. Ca 2+ , Mn 2+ , and Zn 2+ had no effect on activity, while EDTA, Fe 2+ , and Fe 3+ caused partial inhibition in extracts incubated without substrate for 1 h at 25C and pH 5.8. The deacetylase in the mycelial extract and in the culture medium was slightly activated by Co 2+ . The differences in temperature optima and thermal stability of deacetylase and hydrolytic enzymes can be used for controlling the degree of hydrolysis of chitosan, while the difference in pH stability has been used for prepurification, resulting in 3-fold increase in specific activity of deacetylase.