On Colloidal Ampholytes : The Effect of Neutral Salts on Isoionic Bovine Serum Albumin and the Dissociation Constant of its Carboxyl Groups between pH 2.0 and 5.0

University College of Science and Technology, Calcutta-700009 Manuscript received 2 December 1974; revised 17 April 1975; accepted 19 April 1975 The observation of Scatchard, Coleman and Shen that the \(p\)H of isoionic bovine serum mercapt-albumin (BSA) solution rises with increasing concentration of an added neutral salt has been explained on the basis of author's theory without assuming anion binding by BSA. The binding of H+ ions by BSA has been accounted for quantitatively by an equation derived from author's theory on "Colloidal Electrolytes" discussed in previous papers. The dissociation constant of the COOH groups in BSA between \(p\)H 2.0 and 5.0 has been found to be 10-3.18 (i.e., pK= 3.18).