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Titolo:
On the micellar aggregates of alkali metal salts of deoxycholic acid
Autore:
Bonincontro, A; DArchivio, AA; Galantini, L; Giglio, E; Punzo, F;
Indirizzi:
Univ Rome La Sapienza, Dipartimento Chim, I-00185 Rome, Italy Univ Rome LaSapienza Rome Italy I-00185 mento Chim, I-00185 Rome, Italy Univ Aquila, Dipartimento Chim Ingn Chim & Mat, I-67010 Coppito, Italy Univ Aquila Coppito Italy I-67010 ngn Chim & Mat, I-67010 Coppito, Italy Univ Rome La Sapienza, Dipartimento Fis, INFM, I-00184 Rome, Italy Univ Rome La Sapienza Rome Italy I-00184 Fis, INFM, I-00184 Rome, Italy
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 24, volume: 103, anno: 1999,
pagine: 4986 - 4991
SICI:
1520-6106(19990617)103:24<4986:OTMAOA>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
SODIUM DEOXYCHOLATE; X-RAY; TAURODEOXYCHOLATE; GLYCODEOXYCHOLATE; BILIRUBIN; RADIO; EXAFS; PROBE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Giglio, E Univ Rome La Sapienza, Dipartimento Chim, P A Moro 5, I-00185 Rome, Italy Univ Rome La Sapienza P A Moro 5 Rome Italy I-00185 Rome, Italy
Citazione:
A. Bonincontro et al., "On the micellar aggregates of alkali metal salts of deoxycholic acid", J PHYS CH B, 103(24), 1999, pp. 4986-4991

Abstract

The X-ray patterns of lithium (LiDC) and potassium (KDC) deoxycholate fibers, drawn from aqueous micellar solutions, have been interpreted by means of a packing of 8/1 helices formed by trimers. Previously, these helices satisfactorily represented the structure of the sodium (NaDC) and rubidium (RbDC) deoxycholate micellar aggregates. Dielectric measurements show that thetrend of the average electric dipole moment mu of a NaDC monomer as a function of temperature and concentration supports a two-structure equilibrium. The high mu values (32-58 D) can be explained by the remarkable hydration of the NaDC micellar aggregates. The mu moderate decrease when the size of the aggregates increases can agree with the presence of small helices but disagrees with the existence of aggregates that are disordered or have a center (or a pseudocenter) of symmetry. Formerly, it was observed that sodium taurodeoxycholate (NaTDC) micellar aggregates, represented by 7/1 helices, formed by trimers, behave similarly. The contribution to the electrical conductivity of NaDC and NaTDC in aqueous solutions containing NaCl tends to zero by increasing the NaCl concentration, denoting strong interactions between Naf ions and anion aggregates. According to the similar 7/1 and 8/1 helices, which have the Naf ions in their inner part, the micellar size and the fraction of Na+ ions trapped inside the helices increase together. The aggregate apparent hydrodynamic radius (RI,) increases by increasing the ionic strength in the order LiDC > NaDC > KDC > RbDC. Fibers drawn from solutions containing two cations at the same concentration show that the affinity for the anionic structure seems to follow the order Li+ > Na+ > K+ > Rb+ athigh ionic strength. The Rh values VS the mole fractions of Li+ and Rb+ orNa+ and K+ at lower ionic strength are fitted by straight lines. Probably,the free energy gains, associated with the cation and anion transfer from the bulk solution to the micellar aggregates, are almost equal for the foursalts at lower ionic strength.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 27/09/20 alle ore 00:59:24