title: Conformational changes in fibrous elastin due to calcium ions.
abstract: A column packed with calcium-free bovine aorta elastin provided good separations of mixtures of bile salts when water was the moving phase. Tritium-labelled cholesterol was applied to the column using dilute solutions of taurodeoxycholate in Tris-NaCl buffers as solvent. The cholesterol was quantitatively eluted as a narrow peak in a rising gradient of taurodeoxycholate. When Na+ in the buffer was replaced by Ca2+ elution of the labelled cholesterol was delayed. Control experiments in which the elastin fibres were replaced as the column packing by an inert stationary phase consisting of n-butanol immobilized by silane-treated Celite showed that the effect of the change from Na+ to Ca2+ on the solvent properties of taurodeoxycholate was small and in the opposite direction. The experiments indicated that the replacement of sodium by calcium as the ionic environment of fibrous elastin produced a configurational change towards increasing hydrophobic character.
mesh_terms: D000818:Animals; D001011:Aorta; D001647:Bile Acids and Salts / Q000302:isolation & purification*; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D002635:Chenodeoxycholic Acid / Q000302:isolation & purification; D002784:Cholesterol / Q000302:isolation & purification*; D002845:Chromatography; D003840:Deoxycholic Acid / Q000302:isolation & purification; D004549:Elastin; D005998:Glycine / Q000302:isolation & purification; D008095:Lithocholic Acid / Q000302:isolation & purification; D011485:Protein Binding; D011487:Protein Conformation; D012964:Sodium / Q000494:pharmacology; D013654:Taurine / Q000302:isolation & purification; D013656:Taurocholic Acid / Q000302:isolation & purification
chemical_list: D001647:Bile Acids and Salts; D003840:Deoxycholic Acid; D002635:Chenodeoxycholic Acid; D013654:Taurine; D013656:Taurocholic Acid; D008095:Lithocholic Acid; D004549:Elastin; D002784:Cholesterol; D012964:Sodium; D002118:Calcium; D005998:Glycine