title: 23Na-NMR study of ion transport across vesicle membranes facilitated by phenylalanine analogs of gramicidin.
abstract: The transport of Na+ ions across phosphatidylcholine/phosphatidylglycerol large unilamellar vesicle membranes facilitated by phenylalanine analogs of gramicidin A has been studied using 23Na-NMR spectroscopy. The four analogs studied were Phe9-, Phe11-, Phe13-and Phe15-gramicidin A. These analogs were found to transport Na+ ions in the following order Phe15 > Phe13 > Phe11 > Phe9. The entropy and enthalpy of activation for the transport of Na+ ions were determined for each analog. A correlation is made between the activation enthalpies and the single channel conductance values of the analogs.
authors.affiliation: Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701.
authors.forename: J F
authors.initials: JF
authors.lastname: Hinton
authors.forename: P L
authors.initials: PL
authors.lastname: Easton
authors.forename: D K
authors.initials: DK
authors.lastname: Newkirk
authors.forename: D C
authors.initials: DC
authors.lastname: Shungu
mesh_terms: D006096:Gramicidin / Q000737:chemistry*; D017136:Ion Transport; D009682:Magnetic Resonance Spectroscopy; D008566:Membranes / Q000378:metabolism; D010649:Phenylalanine / Q000031:analogs & derivatives*; D012964:Sodium / Q000378:metabolism*; D013696:Temperature; D014364:Tryptophan
chemical_list: D006096:Gramicidin; D010649:Phenylalanine; D014364:Tryptophan; D012964:Sodium