Nuclear magnetic resonance gramicidin

Urry and coworkers 4 O 1 1 proposed a left-handed helical structure for gramicidin A. This conformation can undergo ion induced relaxations which provides a mechanism for the movement of the ion along the channel. These workers confirmed this proposed structure by nuclear magnetic resonance spectrometry1 2. 

Using circular dichroism and nuclear magnetic resonance spectrometry, Veatch and coworkers1 established that four conformational species of gramicidin A exist in solution. Two were postulated to be helixes of opposite handedness. 

Nuclear Magnetic Resonance has been used to establish the conformation of the pure fractions of the gramicidin complex1 2. 

Left and center Two gramicidin A molecules associate to span a cell membrane. Right Axial view showing ion channel. [Structure from B. Roux, "Computational Studies of the Gramicidin Channel." Acc. Chem. Res. 2002,35,366. based on solid-state nuclear magnetic resonance. Schematic at left from L. Stryer. Biochemistry,... 

Cross TA. Solid-state nuclear magnetic resonance characterization of gramicidin channel structure. Methods Enzymol 1997 289 672-696. 

The nuclear magnetic resonance is the most powerful technique in the composite approach, as proved by the fact that application of NMR spectroscopy has had many important results in the study of detailed spatial structures and conformational dynamics of peptides in solution. These results have had a significant impact on the understanding of physiological mechanism of action of such substances as gramicidins, oxytocin, valinomycin, etc. [for a review, see(l)]. ... 

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