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Titolo:
NA K COMPETITIVE TRANSPORT SELECTIVITY OF (221)C-10-CRYPTAND - EFFECTS OF PH AND CARRIER CONCENTRATION/
Autore:
LOISEAU A; HILL M; MULLIERT G; CASTAING M;
Indirizzi:
UNIV PARIS 07,INSERM,U251,BP 416 F-75018 PARIS FRANCE UNIV PARIS 07,INSERM,U251 F-75018 PARIS FRANCE UNIV PARIS 11,FAC SCI ORSAY,BIOENERGET MEMBRANAIRE LAB F-91405 ORSAY FRANCE INST JACQUES MONOD,DEPT BIOL SUPRAMOLEC & CELLULAIRE F-75005 PARIS FRANCE
Titolo Testata:
Biochimica et biophysica acta. Biomembranes
fascicolo: 1, volume: 1235, anno: 1995,
pagine: 21 - 32
SICI:
0005-2736(1995)1235:1<21:NKCTSO>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
IONIZABLE MOBILE CARRIER; LIPID BILAYER-MEMBRANES; ION-TRANSPORT; MEDIATED TRANSPORT; SODIUM-TRANSPORT; DEPENDENCE; IONOPHORE; ALKALI; (221)C10-CRYPTAND; ACTIVATION;
Keywords:
CRYPTAND; ALKALI CATION TRANSPORT KINETICS; COMPETITIVE TRANSPORT SELECTIVITY; PH; LIPID MEMBRANE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
A. Loiseau et al., "NA K COMPETITIVE TRANSPORT SELECTIVITY OF (221)C-10-CRYPTAND - EFFECTS OF PH AND CARRIER CONCENTRATION/", Biochimica et biophysica acta. Biomembranes, 1235(1), 1995, pp. 21-32

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, an ionizable mobile carrier. The experiments were performed at various pH values (7.7 and 8.7) and carrier concentrations (0.1, 0.5 and 1.0 mu M) in order to quantifythe effects of these parameters on the Na/K competitive transport selectivity of this mobile carrier. At any given pH and carrier concentration, the apparent affinity of (221)C-10 for Na+ was higher and less dependent on the concentration of the other competing ion than that forK+. The Na/K competitive transport selectivity (S-C(Na/K)) of (221)C-10 increased linearly with the Na+ concentrations, decreased hyperbolically with increasing those of K+ and was independent of the pH and ofthe carrier concentration. In equimolecular ionic mixtures, this competitive selectivity amounted to about 1.5 and when the pH rose, the carrier selectivity for Na+ over K+ ions was enhanced by cation competition compared to transport of cations as unique substrates. 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, the Michaelis parameters of the cations and the pH. The reaction order in Na+ (n(Na)) increased significantly with decreasing the pH and the K+ concentration. The results are discussed in terms of the structural, physico-chemical and electrical characteristics of carriers and complexes.

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Documento generato il 20/01/21 alle ore 15:43:46