warfarin and 3-carboxy-4-methyl-5-propyl-2-furanpropionic-acid

Two dicarboxylate endogenous substances, bilirubin (BR) and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), have a very high affinity to human serum albumin (HSA). This study was undertaken to clarify the existence of a dicarboxylate binding site on HSA.. Chemical modification, pH dependent binding and X-ray crystallographic analysis were performed to characterize these dicarboxylate binding sites.. It was found the binding behavior for dicarboxylates was different from typical site I ligands such as warfarin (WF) and phenylbutazone (PB) and that electrostatic interaction was an important factor for their binding to HSA. Moreover, His residues were considered to play an important role in pH dependent binding of dicarboxylic acids but in a different manner from the site I ligands. X-ray crystallography of CMPF and BR revealed the distances between the two carboxyl groups in their chemical structures were 5.854 A and 9.979 A, respectively. This difference may be reflected in pH dependent binding. Using fluorescent probe displacement, we attempted to identify the binding site for monocarboxylate derivatives of CMPF and investigated the role of individual carboxyl group in the recognition of the binding site. The results suggested two carboxyl groups were important for the specific binding of CMPF to site I.. The binding site for dicarboxylic acids is located in subdomain IIA, which includes site I, on the HSA molecule. Electrostatic interaction is an important driving force for binding to HSA.

Topics: Bilirubin; Binding Sites; Binding, Competitive; Dicarboxylic Acids; Furans; Humans; Hydrogen-Ion Concentration; Ligands; Phenylbutazone; Propionates; Protein Conformation; Serum Albumin; Warfarin

The interaction of uremic toxins including indole-3-acetic acid (IA), indoxyl sulfate (IS), hippuric acid (HA) and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) with human serum albumin (HSA) has been investigated by three methods of fluorescent probe displacement, ultrafiltration and equilibrium dialysis. The binding parameter of CMPF was found to have the strongest affinity (10(7)M-1) among all the uremic toxins studied. Competitive experiment based on the method of Kragh-Hansen suggested that IA, IS and HA bind to site II, whereas CMPF binds to site I. The present limited data indicated that the four uremic toxins caused inhibition to any endo- or exogenous substances on HSA.

Topics: Binding Sites; Dansyl Compounds; Furans; Hippurates; Humans; Indoleacetic Acids; Indoles; Propionates; Sarcosine; Serum Albumin; Uremia; Warfarin

Impaired binding of anionic drugs to serum albumin in patients with uremia is thought to be due to the accumulation of endogenous substances that bind to albumin. In this study the displacement by the anionic drugs diazepam, warfarin, and salicylic acid, which are known to be representative drugs for the binding sites on the albumin molecule, of several endogenous ligands that bind to albumin in uremic serum was examined. The free fractions of the ligands bound to albumin were separated by ultrafiltration in the presence and the absence of test drugs and assayed by high-performance liquid chromatography. Diazepam displaced indoxyl sulfate (IS), hippuric acid (HA), and indole-3-acetic acid (IAA), and warfarin displaced IS, HA, ISAA, and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid from serum albumin. However, salicylic acid did not displace the substance examined. The methods reported here are useful for determining the binding sites of the endogenous ligands on albumin and to clarify the drug-ligand interaction on albumin molecule in uremic serum.

Topics: Binding Sites; Furans; Hippurates; Humans; Indican; Indoleacetic Acids; Propionates; Protein Binding; Salicylates; Salicylic Acid; Serum Albumin; Uremia; Warfarin