Aim. To study the influence of zinc ions on the ATP-hydrolase reaction, catalyzed by myosin, and the superprecipitation (SPP) reaction of actomyosin cardiac muscle. Methods. Preparative protein chemistry, ion-exchange chromatography and optical spectroscopy. Results. It was shown that zinc ions in the range of concentrations 0.1–5 mM inhibit the Ca²⁺-ATPase myosin activity and Mg²⁺-dependent SPP reaction of actomyosin cardiac muscle. The original results were compared with the well-known data on the influence of other bivalent ions – strontium and cadmium – on the above processes. Conclusions. Zinc ions, probably by replacing the calcium and magnesium ions in the SPP reaction and ATP-hydrolase process, can modulate the actinmyosin interaction by changing the functional characteristics of muscle actomyosin macromolecules. The obtained results extend the existing understanding of the mechanisms of physical and chemical environmental factors influence, in particular metal ions, on the enzymatic activity of ATP-hydrolases, namely myocardium myosin ATPase.

Keywords: myosin, actomyosin, ATPase, zinc ions, cardiac muscle