The action of thiol inhibitors on the interaction of F-actin and heavy meromyosin

Abstract

Low concentrations of phenylmercuric acetate and p-chloromercuribenzoate inhibit the ability of F-actin to form a viscous complex with H-meromyosin at low ionic strength. N-Ethylmaleimide was not effective under similar conditions. The adenosine triphosphatase of H-meromyosin is strongly activated by Mg2+ ions in the presence of F-actin poisoned with concentrations of phenylmercuric acetate and p-chloromercuribenzoate, which markedly inhibit interaction as measured by viscosity changes with adenosine triphosphate. The ability of H-meromyosin to form a complex with F-actin is not inhibited by concentrations of thiol reagents that inhibit the complex-forming properties of the latter protein. At higher concentrations of organomercurials and N-ethylmaleimide the enzymic activity of H- meromyosin is destroyed but substantial interactions with F-actin as measured viscometrically survive.