Properties of chitin deacetylase from crude extracts of Mucor rouxii mycelium

The catalytic properties of chitin deacetylase from Mucor rouxii were studi ed with the aim of using the results for control of the properties of chito san prepares by enzymatic deacetylation. A crude deacetylase extract from t he mycelium of Mucor rouxii exhibited maximal activity at pH 5.8 with both water-soluble and acid-soluble chitosan. The extracellular enzyme of the cu lture medium exhibited maximal activity at pH 4.8. The deacetylase in the c rude extract was stable over the pH range of 4.1-8.9 at 25C, retaining 85-1 00% of maximal activity at 40C. The extract was most active towards acid-so luble chitosan at 50C and pH 5.8. Chitin deacetylase was stable to 40C when incubated without substrate, with 85% of the activity retained at 50C. Ca2 +, Mn2+, and Zn2+ had no effect on activity, while EDTA, Fe2+, and Fe3+ cau sed partial inhibition in extracts incubated without substrate for 1 h at 2 5C and pH 5.8. The deacetylase in the mycelial extract and in the culture m edium was slightly activated by Co2+. The differences in temperature optima and thermal stability of deacetylase and hydrolytic enzymes can be used fo r controlling the degree of hydrolysis of chitosan, while the difference in pH stability has been used for prepurification, resulting in 3-fold increa se in specific activity of deacetylase.