Abstract
Properties of a protease inhibitor from Penicillium cyclopium were studied. The pH range of the inhibitor action is restricted to acid pH, optimally at pH 3. Increasing temperature accelerates its action upon enzyme. The inhibitor causes enzyme inactivation in proportion to its concentration. It is fairly stable in an acid solution but unstable in an alkaline solution. It undergoes destruction by heat, hydrogen peroxide and ascorbic acid. The inhibitor reversibly combines with Al3+, Fe3+, Ag+ and Cu2+ to produce a precipitate. Salts interfer with the inhibitor activity. Generally, acid proteases from various penicillia are susceptible to the inhibitor while those from other genera are resistant.
