STUDIES ON SOME PHYSICOCHEMICAL ASPECTS OF MYOSIN .1. BINDING OF LONG-CHAIN AMPHIPHILES TO MYOSIN

The binding of long-chain cationic and anionic amphiphiles to fish myosin has been studied extensively using the equilibrium dialysis technique. The extent of binding has been found to be highly dependent on the physico-chemical conditions of the system such as temperature, pH, ionic strength and presence of inorganic salts, as well as on the nature of the ligand. From the experimental results, some thermodynamic parameters like the standard free energy change (DELTA-G-degrees), standard enthalpy change (DELTA-H-degrees) and standard entropy change (DELTA-S-degrees) at a well defined standard state of reference have been evaluated. For cetyltrimethylammonium bromide binding, a compensation effect between DELTA-S-degrees and DELTA-H-degrees has been observed for different temperatures while for sodium dodecyl sulphate binding, both DELTA-S-degrees and DELTA-H-degrees are found to be insensitive to change in temperature. It has been observed that the binding sites of myosin are highly heterogeneous and the operating forces for both cationic and anionic ligands have been discussed in detail.