Papain membrane on a collodion matrix: preparation and enzymic behavior.

A stable papain membrane has been prepared on a collodion matrix by absorbing papain in a collodion membrane and then cross-linking the papain with bisdiazobenzidine 3,3'-disulfonic acid. The pH-dependence of the activity of the enzyme membrane on the low-molecular-weight substrate, benzoylarginine ethyl ester, was found to differ from that of crystalline papain; the activity was low in the neutral pH range where the native enzyme has its optimum and high at alkaline pH. This anomalous behavior is due to a lowering of the local pH within the membrane as a result of the release of acid by the enzymic hydrolysis of the ester substrate.