Studies on the Inhibitors of Thiol-enzymes. I

Influence of Metals and Organometallic Compounds on the Activity of Papain

Abstract

Substances that inhibit enzymes, which have SH as the active group, were examined systematically in order to aid the studies on chemotherapeutics, and inhibitory action of various metal ions, metalloid ions, and organic compounds containing such metal elements against Papain was compared. The substances tested were mercury and tin as the metal, arsenic as the metalloid as their salts, phenylmercuric acetate, ethylmercuric phosphate, diethyltin sulfate, and ethylarsinic acid, as the organometallic compounds.
It was thereby found that there was a threshold of inhibition by mercury compounds, at 2×10^-5 M of mercuric chloride and ethylmercuric phosphate, and at 4×10^-5 M of phenylmercuric acetate. There was almost no effect on enzyme activity by the addition of arsenic oxide or ethylarsinic acid, while diethyltin sulfate causes a weak inhibition. In the case of stannous chloride and stannous sulfate, on the contrary, some activation of enzyme activity was observed.