Summary: The proteolytic activation and inactivation of chitin synthase (EC 2.4.1.16) from Neurospora crassa was studied. Chitin synthase was found mostly in an inactive form which could be activated either endogenously or by the addition of exogenous proteases. The addition of protease inhibitors prevented the endogenous activation of the enzyme. The stability of the inactive enzyme improved when buffers of pH values between 8·2 and 9·5 were employed. The inactive enzyme was mainly associated with membranous fractions.
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