STUDIES ON SOME PHYSICOCHEMICAL ASPECTS OF MYOSIN .2. BINDING OF LONG-CHAIN AMPHIPHILES TO A MIXTURE OF MYOSIN, SERUM-ALBUMIN AND GELATIN

The binding capacity of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) to three structurally different proteins, rod-shaped myosin, ellipsoidal bovine serum albumin (BSA) and random-coiled gelatin, has been compared. Results of previous workers [M. Sen, S.P. Mitra and D.K. Chattoraj, Indian J. Biochem. Biophys., 17 (1980) 370, 405; Colloids Surfaces, 2 (1981) 259] have been utilised for BSA and gelatin and those for myosin have been discussed in Part 1 of this series. Interaction of the surfactants with a binary mixture of myosin-BSA and a ternary mixture of myosin-BSA-gelatin has been studied by the equilibrium dialysis technique at various protein compositions, pH values, ionic strengths and temperatures. Experimental values of the maximum extent of binding (GAMMA(R)m) have been compared with the respective theoretically calculated ideal values of maximum extent of binding, i.e. (GAMMA(R)m)i. For both binary and ternary mixtures the extent of deviation between the experimental and ideal values is higher for SDS than for CTAB. Moreover, this deviation is dependent on the percentage composition of the protein mixture. From the computation of the standard free energy changes for binding interaction, the deviations have been analysed on the basis of protein-protein and protein-surfactant interactions.