[Effect of the irradiation conditions on the radiation inactivation of subtilisin-72].

A comparative study was made of gamma-inactivation of subtilisin-72 solutions in 5 X 10(-3) M acetate buffer and 0.1 M NaCl in the presence and absence of Ca2+ ions. It was shown that the acetate buffer had a protective action, and the influence of Ca2+ ions depended on the ionic strength of the solution. In general, Ca2+ ions exerted a stabilizing effect irrespective of the subtilisin concentration in the acetate buffer, but this effect competed with the destabilizing influence of the ionic strength increased by Ca2+ ions.