Competitive binding of two drugs for a single binding site on albumin: a circular dichroic study

Abstract

Sulphaethidole has been previously shown to have two classes of binding site on bovine serum albumin (BSA). Only the primary binding site is capable of inducing optical activity in the drug. Drugs that bind to the same primary binding site as sulphaethidole, but do not become optically active themselves on binding, reduce the size of the circular dichroism signal in competitive binding studies with sulphaethidole. The binding constant for such antagonists can be calculated. It appears that a range of acidic drugs share the same primary binding site on bovine serum albumin; basic drugs do not compete for this site. 1973 Royal Pharmaceutical Society of Great Britain