CHANNEL-TYPE MOLECULAR-STRUCTURES .4. TRANSMEMBRANE TRANSPORT OF ALKALI-METAL IONS BY BOUQUET MOLECULES

被引：73

作者：

PREGEL, MJ ^{[1
]}

JULLIEN, L ^{[1
]}

CANCEILL, J ^{[1
]}

LACOMBE, L ^{[1
]}

LEHN, JM ^{[1
]}

机构：

[1] COLL FRANCE,CHIM INTERACT MOLEC LAB,F-75005 PARIS,FRANCE

来源：

JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1995年 / 03期

关键词：

D O I：

10.1039/p29950000417

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

This report describes transport experiments with 'bouquet' molecules designed to act as artificial ion channels. The 'bouquets' are based on a central macrocycle which is either an 18-crown-6 (B-M) or a cyclodextrin derivative (B-CD) to which are attached poly(ethylene oxide) [poly(oxyethylene)] chains (B-M(o) and B-CD(o)) or polyalkyl chains (B-M(c) and B-CD(c)) tipped with carboxylate end-groups. The 'bouquets' were studied in liposomes prepared from egg phosphatidylcholine (egg PC), dipalmitoyl phosphatidylcholine (DPPC) and a mixture of egg PC, stearylamine and cholesterol. Opposing gradients in Li+ and Na+ concentration were created and the transport of alkali-metal ions down their concentration gradients was followed directly by Li-7 and Na-23 NMR spectroscopy. 'Bouquets' were found to cause a one-for-one exchange of Na+ for Li+ (antiport). In order to estimate transport rates, the extent of Na+ entry into liposomes was followed as a function of time. All 'bouquets' transported ions at similar rates in fluid membranes. Comparison of transport rates in fluid- (egg PC) and gel-state membranes (DPPC) was used to distinguish carrier and channel mechanisms. Control experiments demonstrated that a known carrier (monensin A) gave significantly lower transport rates in gel-state membranes. Two 'bouquets', B-M(c) and B-CD(o), were found to transport Na+ at similar rates in fluid- and gel-state membranes; this suggests that ion passage occurs preferentially by the channel mechanism and not by the carrier mechanism. Variation of transport rate with 'bouquet' concentration was probed for B-M(o) and B-M(c) and the rates were found to increase with B-M(c) concentration but not with B-M(o) concentration. Since the transport rate is expected to be proportional to transporter concentration in both the carrier and channel mechanisms, this indicates that B-M(o) uses neither a carrier nor a channel mechanism. The mechanism by which 'bouquet' molecules operate and the criteria which may be used to decide whether functioning channels have been created are discussed.

引用

页码：417 / 426

页数：10

共 39 条

[1] Darnell J., Lodish H., Baltimore D., Molecular Cell Biology., (1986)
[2] Kohlwein S.D., J. Chem. Ed., 69, (1992)
[3] Lauger P., Angew. Chem., Int. Ed. Engl., 24, (1985)
[4] Van Beijnen A.J.M., Nolte R.J.M., Zwicker J.W., Drenth W., Rec. Trav. Chim. Pays Bas., 101, (1982)
[5] Nakano A., Xie Q., Mallen J.V., Echegoyen L., Gokel G.W., J. Am. Chem. Soc., 112, (1990)
[6] Ghadiri M.R., Granja J.R., Buehler L.K., Nature., 369, (1994)
[7] Fuhrhop J.-H., Liman U., J. Am. Chem. Soc., 106, (1984)
[8] Fuhrhop J.-H., Liman U., David H.H., Angew. Chem., Int. Ed. Engl., 24, (1985)
[9] Menger F.M., Davis D.S., Perischetti R.A., Lee J.J., J. Am. Chem. Soc., (1990)
[10] Fyles T.M., Kaye K.C., Pryhitka A., Tweddel J., Zojaji M., J. Supramol. Chem.

← 1 2 3 4 →