INTERACTION OF OXYTETRACYCLINE WITH OVINE SERUM ALBUMIN

Abstract

The interaction of oxytetracycline with ovine serum albumin was studied. The apparent association constants, the number of binding sites and the thermodynamic parameters of the interaction were established using the equilibrium dialysis technique at 15, 20 and 25" C. At the three temperatures, one binding site was found for the ovine serum albumin.The apparent association constants ranged from 11845.54 to 13361.10 M^{-1 .The decrease in the constants, due to the decrease in temperature, suggests a loss of affinity between the oxytetracycline and the ovine serum albumin. The spontaneity of the interaction was established, based on the negative value of the standard free energy (AG). The decrease of spontaneity when the temperature drops was demonstrated by the variation of AG at the different temperatures. This fact arises from the loss of affinity between the oxytetracycline and the ovine serum albumin. Furihermore, the interaction was found to occur endothermically (standard enthalpy (AH >O), with stability (standard entropy (AS >O) and is regulated. fundamentally by electrostatic attraction.}