Biophysical Journal 25: 535-540 (1979)
© 1979 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Monoi, H Articles by Uedaira, H Search for Related Content PubMed PubMed Citation Articles by Monoi, H Articles by Uedaira, H

Na+ interacting with gramicidin D. A nuclear magnetic resonance study.

ABSTRACT

23Na nuclei in a milk-white emulsion composed to nonionic surfactant and higher alcohol in saline were characterized by single values of T1 and T2 and a single Larmor frequency. In the presence of small amounts of gramicidin D (Dubos), the relaxations of 23Na were greatly accelerated, and the transverse relaxation was a sum of two decaying exponentials. But only a single T1 was observed; it was roughly equal to the slow T2. The slow T2 accounted for about 40% of the total resonance intensity. The relaxation rates increased linearly with the increase of the gramicidin concentration. The absorption signal consisted of a narrow and a broad line, both centered at the same frequency. The present results suggest that nuclear magnetic resonance spectroscopy is a useful tool for studying the nature of ion-permeable channels of biological membranes, even when the channel has no ionizable groups.