The effect of serum albumin, surfactant and their mixture on the reduction of a cobalt(III) complex by ascorbic acid

Kinetic investigations on the reduction of CoIII-complex by a biologically active antioxidant molecule, ascorbic acid in a buffer medium of pH 9.0 have been performed using spectroscopic techniques. The reaction has been carried out in presence of a protein, bovine serum albumin (BSA), n-cetyltrimethylammonium bromide (CTAB) and their mixtures. The reaction rate changes remarkably on addition of protein. Unlike the complex, experimental results depict extensive binding of detergent and ascorbate anions with BSA. Both native and cooperative binding have been observed for CTAB–BSA interaction. But only native binding at specific binding sites have been observed for ascorbic acid–BSA interaction. The reactant molecules prefer to bind with domain I and III over II of the BSA molecules. Denaturing action of urea releases the protein bound ascorbates into bulk. The experimental findings have been further verified from the conductometric and circular dichroism studies.