Mohammad Najmuddin Khan

Abstract

Objective: Besides bilirubin and fatty acids are more important among the physiological ligands transported by albumin, drugs constitute the major class of exogenous ligands transported by albumin. Considering the total number of ligands bound to albumin, it is inconceivable to think of the same number of ligand binding sites on albumin molecule, so it seems that same binding sites are shared by several compounds. Thus it is possible that some ligands may be displaced from albumin by other ligands. Various drugs are well known displacer of bilirubin from albumin. Materials and Methods: In the present communication the binding of three drugs namely, Indomethacin, chlorpromazine and oxyphenbutazone to serum albumins (BSA and SSA) under different conditions of pH and ionic strength have been studied by fluorescence quenching technique in order to ascertain the role of various non – covalent interactions. Results and Discussion: The results suggest that in case of indomethacin, a decrease in binding was observed on increasing the ionic strength, indicating the involvement of electrostatic interactions whereas in case of chlorpromazine and oxyphenbutazone, significant increase in binding was noticed on increasing the ionic strength was suggestive of the involvement of hydrophobic interactions. The extent of binding of these drugs was more pronounced in BSA compared to SSA. Keywords: Sheep serum albumin, Bovine serum albumin, Human serum albumin, Bilirubin binding, Ionic strength, Fluorescence quench, Indomethacin, Chlorpromazine, Oxyphenbutazone.

Open full article page

Abstract

Despite great degree of similarity in the structure and conformation of different serum albumins, they often show marked difference in the ligand binding properties. These differences and similarities would be useful in understanding the molecular basis of ligand binding to serum albumins. In the present communication binding of bilirubin with sheep and bovine serum albumin have been studied by visible difference spectroscopy as a function of pH and ionic strength. The results suggest that the structure of bilirubin binding site in sheep serum albumin is similar to that in bovine serum albumin and that complex between sheep serum albumin and bilirubin is stabilized by electrostatic interactions. Keywords: Sheep serum albumin, Bovine serum albumin, Bilirubin binding, ionic strength, pH.

Open full article page