Transport of Metanil Yellow in the Rat Plasma and Interaction of Its Metabolite, p-Aminodiphenylamine with Serum Proteins

Binding affinity of metanil yellow and its breakdown product p-aminodiphenylamine to serum proteins has been studied employing chromatographic separation on Sephadex G-200 and by paper and polyacrylamide gel electrophoresis. Metanil yellow has more affinity towards albumin than to globulins. The complexing is presumably through electrostatic forces. p-Aminodiphenylamine on the other hand, preferably binds to globulin fractions of serum protein. However, a stable binding with BSA alone was also observed. The binding was quite stable and was accompanied by a shift in absorbance from 430 nm to 500 nm. Aspartic acid moiety of protein was found to be one of the units involved in the binding of p-ADPA to proteins.