Biomaterial Database

Structural features of the hydroxy- and keto-disubstituted bile salts: human serum albumin binding. 1995

B Farruggia, and F Garcia, and G Picó

Departamento de Química-Física, Facultad de Ciencias Bioquímicas y Farmaceuticas, Consejo de Investigaciones de la U.N.R., Rosario, Argentina.

The binding of keto- and hydroxy bile salts to human serum albumin, the identity of the bile salts binding sites and the identification of the amino acids present in these sites were studied. The keto bile salts cholanate-3-one (C3), cholanate-3,6-dione (C3-6) and cholanate-3-hydroxy-6-one (KHC) were found to quench the native fluorescence emission of albumin. This suggested that the tryptophan residue of human albumin (residue 214) is accessible to the keto bile salts and not to the hydroxy parent compounds. The binding of the keto bile salts was characterized by a simple population of binding sites with Ka ranging from 22 x 10(4) M-1 for the mono keto bile salt (C3) down to 4 x 10(4) M-1 for the hydroxy-keto bile salt (KHC). The substitution of an oxo group at carbon C3 in C3-6 molecule for a hydroxy group (KHC) produce a significant decreasing of the interaction, suggesting that the hybridization state of the carbon at C3 in the steroid ring of the bile salt molecule is also an essential requirement for bile salts binding. It was found that bile salts are bound to the benzodiazepine binding site on human albumin (site II), producing a perturbation on site I, fatty acids and bilirubin binding site. The presence of only one substituent at C3 (oxo or OH) produce an important perturbation on the fatty acid binding sites, decreasing the polarity of the its microenvironment, while a little effect was observed for the dihydroxy and di-oxo-substituted BS, suggesting that the hydroxy substituents at C6, C7 and C12 do not interact in a significant manner with the fatty acid binding sites on HSA. The participation of specific amino acids in albumin-bile salt binding sites depends on the polar groups on the bile salt molecules as exemplified by the quantitatively different role of lysyl residues like those interacting with KHC, C3 and C3-6, and tyrosyl residue interacting with KHC. The following amino acids in human albumin were found to play a role in the bile salts-albumin interaction: lysyl 195 and 225, several arginyls, histidyl 146 and tyrosyl 411.

UI	MeSH Term	Description	Entries
D003619	Dansyl Compounds	Compounds that contain a 1-dimethylaminonaphthalene-5-sulfonyl group.	Dimethylaminonaphthalenesulfonyl Compounds,Compounds, Dansyl,Compounds, Dimethylaminonaphthalenesulfonyl
D005453	Fluorescence	The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
D005470	Fluorometry	An analytical method for detecting and measuring FLUORESCENCE in compounds or targets such as cells, proteins, or nucleotides, or targets previously labeled with FLUORESCENCE AGENTS.	Fluorimetry,Fluorometric Analysis,Analysis, Fluorometric
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001647	Bile Acids and Salts	Steroid acids and salts. The primary bile acids are derived from cholesterol in the liver and usually conjugated with glycine or taurine. The secondary bile acids are further modified by bacteria in the intestine. They play an important role in the digestion and absorption of fat. They have also been used pharmacologically, especially in the treatment of gallstones.	Bile Acid,Bile Salt,Bile Salts,Bile Acids,Acid, Bile,Acids, Bile,Salt, Bile,Salts, Bile
D001663	Bilirubin	A bile pigment that is a degradation product of HEME.	Bilirubin IX alpha,Bilirubin, (15E)-Isomer,Bilirubin, (4E)-Isomer,Bilirubin, (4E,15E)-Isomer,Bilirubin, Calcium Salt,Bilirubin, Disodium Salt,Bilirubin, Monosodium Salt,Calcium Bilirubinate,Hematoidin,delta-Bilirubin,Bilirubinate, Calcium,Calcium Salt Bilirubin,Disodium Salt Bilirubin,Monosodium Salt Bilirubin,Salt Bilirubin, Calcium,delta Bilirubin
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D012709	Serum Albumin	A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.	Plasma Albumin,Albumin, Serum
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D014212	Tretinoin	An important regulator of GENE EXPRESSION during growth and development, and in NEOPLASMS. Tretinoin, also known as retinoic acid and derived from maternal VITAMIN A, is essential for normal GROWTH; and EMBRYONIC DEVELOPMENT. An excess of tretinoin can be teratogenic. It is used in the treatment of PSORIASIS; ACNE VULGARIS; and several other SKIN DISEASES. It has also been approved for use in promyelocytic leukemia (LEUKEMIA, PROMYELOCYTIC, ACUTE).	Retinoic Acid,Vitamin A Acid,Retin-A,Tretinoin Potassium Salt,Tretinoin Sodium Salt,Tretinoin Zinc Salt,Vesanoid,all-trans-Retinoic Acid,beta-all-trans-Retinoic Acid,trans-Retinoic Acid,Acid, Retinoic,Acid, Vitamin A,Acid, all-trans-Retinoic,Acid, beta-all-trans-Retinoic,Acid, trans-Retinoic,Potassium Salt, Tretinoin,Retin A,Salt, Tretinoin Potassium,Salt, Tretinoin Sodium,Salt, Tretinoin Zinc,Sodium Salt, Tretinoin,Zinc Salt, Tretinoin,all trans Retinoic Acid,beta all trans Retinoic Acid,trans Retinoic Acid