Binding of Digitoxin to Human Serum Albumin: Influence of Free Fatty Acids,Bile Acids,and Protein Unfolding on the Digitoxin-Albumin Interaction

Abstract The binding of digitoxin to purified human serum albumin was studied under equilibrium conditions. The binding affinity was uninfluenced by the strongly bound free fatty acids of the albumin. All bile acids studied were found to inhibit the binding of digitoxin to albumin. Cholic acids and desoxycholic acid induced a competitive inhibition of the digitoxin-albumin interaction without any physical signs of protein unfolding. Surface active organic anions, known to produce conformational changes of albumin, were found to be powerful inhibitors of the digitoxin-albumin interaction.