[Some properties of peptidase from rat heart, breaking down luliberin]. / Nekotorye svoistva peptidazy iz serdtsa krysy, rasshchepliaiushchei liuliberin.

The properties of rat heart peptidase hydrolyzing luliberin were studied. This peptidase was shown to be a sulfhydryl metalloenzyme with m.w. of about 100000. The maximal enzyme activity was observed at neutral values of pH Ca2+ (5 X 10(-6) M) increased the enzyme activity by 50%, thus being indicative of an anomalous dependence of the enzyme activity of substrate concentration. At luliberin concentrations of 10(-7)-10(-6) M the enzyme activation by Ca2+ was considerably reduced and returned to the initial level when the peptide concentration was increased up to 10(-5) M. It was assumed that the peptidase under study is a regulatory enzyme whose activity depends on concentrations of Ca2+ and of the reaction substrate, luliberin.