The Effects of Gamma Irradiation on Some Properties of Two Aeromonas Proteinases

Abstract

The proteinases A and B of Aeromonas liquefaciens and proteinase B of Aeromonas salmonicida have, in the crude and purified state, been exposed to various doses of γ-irradiation from a Co60 source, and the D37 values indicate that the proteinase A is the most resistant. Casein was shown to have a marked protective effect on both proteinases during the irradiation, and while solutions of the purified enzymes were inactivated by doses usually used for food pasteurization, the crude enzymes, or solutions of purified enzymes to which casein was added, required doses usually used for food sterilization before being inactivated. Only minor effects of the environmental pH were observed. The antigenic properties of the enzymes seemed to be qualitatively unchanged in solutions exposed to 150 krad as observed using the casein precipitation inhibition test, and the irradiated proteinases were also inhibited by the naturally occurring proteinase inhibitors in the immune sera. The enzymoserological properties were not influenced by the changes in electrophoretic migration which were demonstrated by the zymogram technique. These proteinases are suitable as models for the examination of the physical properties of food spoiling enzymes and also for taxonomical work.