UNUSUAL BEHAVIOR OF THE INTERACTION OF SODIUM NORMAL-DODECYL SULFATE WITH CALF THYMUS HISTONE H2B IN AQUEOUS-SOLUTION

The binding of sodium n-dodecyl sulphate (SDS) to calf thymus histone H2B was studied in the pH range 3.2-10 by equilibrium dialysis at 27 and 37-degrees-C. The binding data have been used in terms of the Schatchard equation showing unusual plots with minima. No theoretical model gives Scatchard plots with such conditions, except for a combination of two types of binding with large differences in the Hill coefficients and binding affinity, i.e. a combination of negatively and positively cooperative binding sites.