Protein Bindings. V. Binding of N⁴-Acetylsulfonamides to Bovine Serum Albumin

Abstract

Binding constant, K_ac, for 11 N⁴-acetylsulfonamides with bovine serum albumin was evaluated spectrophotometrically utilizing the competion between 2-(4'-hydroxyphenylazo) benzoic acid and N⁴-acetylsulfonamides at 37°and 5°, and was compared with K_f, binding constant for free sulfonamides with bovine serum albumin. Free energy and entropy changes for the binding were calculated. The correlations of log (K_ac/K_f) with the fraction of unchanged sulfonamides excreted in the urine after the administration, and with half-life for elimination of sulfonamides from human blood plasma were indicated to be significant.