The binding of 3,6-disubstituted bile salts to human serum albumin induces conformational change on the molecule of this protein. 1999

B Farruggia, and G A Picó
Departamento de Química-Física, Facultad de Ciencias Bioquímicas y Farmacéuticas and CONICET-CIUNR, Universidad Nacional de Rosario, Argentina.

The binding of 3,6-hydroxy and keto disubstituted bile salts to human serum albumin was studied using differential scanning calorimetry, fluorescence spectroscopy and circular dichroism. The bile salts assayed did not produce any modification in the shape of the albumin thermogram, its thermal unfolding process in their presence being reversible; however, an increase in the enthalpy of unfolding and in the Tm was observed in the presence of 3,6-diketo and 3-hydroxy-6-keto bile salts. These two derivatives induced a negative circular dichroism spectrum of the protein around 280-290 nm, quenched the native fluorescence of the buried tryptophan of albumin and induced energy transfer between 1 aniline-8-naphthalene sulfonate and the buried tryptophan 214 of albumin. The presence of a keto group at C6 in the steroid ring of the bile salts plays an important role in producing slight movement of the albumin domains, increasing the distance between domains I and II.

UI MeSH Term Description Entries
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D011487 Protein Conformation The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain). Conformation, Protein,Conformations, Protein,Protein Conformations
D002152 Calorimetry, Differential Scanning Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample. Differential Thermal Analysis, Calorimetric,Calorimetric Differential Thermal Analysis,Differential Scanning Calorimetry,Scanning Calorimetry, Differential
D002942 Circular Dichroism A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D004735 Energy Transfer The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER. Transfer, Energy
D005456 Fluorescent Dyes Chemicals that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags. Flourescent Agent,Fluorescent Dye,Fluorescent Probe,Fluorescent Probes,Fluorochrome,Fluorochromes,Fluorogenic Substrates,Fluorescence Agents,Fluorescent Agents,Fluorogenic Substrate,Agents, Fluorescence,Agents, Fluorescent,Dyes, Fluorescent,Probes, Fluorescent,Substrates, Fluorogenic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000817 Anilino Naphthalenesulfonates A class of organic compounds which contain an anilino (phenylamino) group linked to a salt or ester of naphthalenesulfonic acid. They are frequently used as fluorescent dyes and sulfhydryl reagents. Naphthalenesulfonates, Anilino
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
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

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