[Sorption of neutral red by actomyosin threads during contraction and heating]

Studies of the equilibrium distribution of the cation dye-neutral red by actomyosin threads allowed to establish the fact that different concentrations of dye reveal the existence of different bonds with contractile proteins. Firm bonds (7.3 ccal/M) are discovered at low dye concentrations, and weaker bonds (4.5 ccal/M) are seen at higher concentrations. The contraction of actomyosin threads evoked by ATP or heating is accompanied with similar changes, i. e. by the diminishing of the maximum dye sorption within the range of low dye concentrations and by the increase in the maximum dye sorption within the range of high concentrations.