Phospholipid requirement of microsomal chitinase fromMucor mucedo

Abstract

Microsomal and supernatant chitinase activities have been prepared from mycelial cultures ofMucor mucedo. Studies of their responses to changing temperature and phospholipid composition indicate that the lipid environment is important in regulating membrane-bound chitinase activity, but that supernatant chitinase activity does not have a phospholipid requirement. Membrane-bound chitinase was solubilized by different types of non-denaturing detergents. Maximum solubilization was achieved with 1 mM Zwittergent-14 or 1.2% Triton X-100 (93% and 90% solubilization, respectively). This solubilized chitinase activity could not be activated by protease treatment, i.e., was nonzymogenic, as was the supernatant chitinase. The insoluble residual chitinase activity was, however, zymogenic after treatment with 1.2% Triton X-100, but fully active after treatment with 3% Triton X-100.