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Titolo:
NA K COMPETITIVE TRANSPORT SELECTIVITY OF (221)C-10-CRYPTAND - EFFECTOF TEMPERATURE/
Autore:
MULLIERT G; HILL M; LOISEAU A; CASTAING M;
Indirizzi:
FAC XAVIER BICHAT,INSERM,U251,16 RUE HUCHARD F-75018 PARIS FRANCE FAC XAVIER BICHAT,INSERM,U251 F-75018 PARIS FRANCE INST JACQUES MONOD,DEPT BIOL SUPRAMOLEC & CELLULAIRE F-75005 PARIS FRANCE UNIV PARIS 11,FAC SCI,BIOENERGET MEMBRANAIRE LAB F-91405 ORSAY FRANCE
Titolo Testata:
Biochimica et biophysica acta. Biomembranes
fascicolo: 2, volume: 1193, anno: 1994,
pagine: 263 - 275
SICI:
0005-2736(1994)1193:2<263:NKCTSO>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
IONIZABLE MOBILE CARRIER; LIPID BILAYER-MEMBRANES; MEDIATED ION-TRANSPORT; CATION-TRANSPORT; SODIUM-TRANSPORT; VALINOMYCIN; KINETICS; DEPENDENCE; ACTIVATION; IONOPHORE;
Keywords:
CRYPTAND; ALKALI CATION TRANSPORT KINETICS; COMPETITIVE TRANSPORT SELECTIVITY; TEMPERATURE; LIPID MEMBRANE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
51
Recensione:
Indirizzi per estratti:
Citazione:
G. Mulliert et al., "NA K COMPETITIVE TRANSPORT SELECTIVITY OF (221)C-10-CRYPTAND - EFFECTOF TEMPERATURE/", Biochimica et biophysica acta. Biomembranes, 1193(2), 1994, pp. 263-275

Abstract

The kinetics of the competitive transport of Na+ and K+ ions across the membrane of large unilamellar vesicles (LUV) were determined when transport was induced by (221)C-10-cryptand at various temperatures in order to quantify the temperature-dependence of the Na/K competitive transport selectivity of this ionizable mobile carrier. At any given temperature, the apparent affinity of (221)C-10 for Na+ was higher and less dependent on the concentration of the other competing ion than that for K+. Its enthalpy for Na+ (Delta H(K-mNa) = 50.6 kJ/mol) was not significantly different from that for K+ (Delta H(K-mK) = 52.7 kJ/mol). The Na/K competitive transport selectivity (S-C(Na/K)) of (221)C-10 increased linearly with the Na+ concentrations and decreased hyperbolically with increasing those of K+. When the cation concentrations wereequal, this competitive selectivity amounted to about 2 at any given temperature. Equations were established to describe the variations of the competitive transport selectivity (S-C) of cryptands, and for comparison of their noncompetitive selectivity (S-NC), with the ionic concentrations and the Michaelis parameters of the cations. It is theoretically demonstrated that the ratio between the competitive and noncompetitive transport selectivities, i.e., S-C/S-NC, of mobile carriers does not depend on the J(max) of the competing ions and that its value amounts to 1 when the specific concentrations (C-S/K-m) of the ions are equal. Under these conditions, the transport selectivity of any given mobile carrier has the same value whether determined from competition or seperated experiments. The reaction order in Na+ (n(Na)) increased significantly as the temperature rose and decreased significantly as the K+ concentration increased. The results are discussed in terms of the structural, physicochemical and electrical characteristics of carriers and complexes.

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Documento generato il 20/01/21 alle ore 14:41:09