Na-23-Nmr Study of Ion-Transport Across Vesicle Membranes Facilitated by Phenylalanine Analogs of Gramicidin
by Hinton, James F.; Easton, Phillip Lee; Newkirk, Donald Keith; Shungu, Dikoma C.
The transport of Na+ ions across phosphatidylcholine/phosphatidylglycerol large unilamellar vesicle membranes facilitated by phenylalanine analogs of gramicidin A has been studied using Na-23-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.
- Biochimica et Biophysica Acta
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- 1878-2434; 0006-3002