Solid-state /sup 15/N NMR of oriented lipid bilayer bound gramicidin A'

Journal Article · Tue Oct 20 00:00:00 EDT 1987 · Biochemistry; (United States)

OSTI ID:5513127

Nicholson, L K; Moll, F; Mixon, T E; LoGrasso, P V; Lay, J C; Cross, T A

Highly oriented samples of lipid and gramicidin A' (8:1 molar ratio) have been prepared with the samples extensively hydrated (approximately 70% water v/w). These preparations have been shown to be completely in a bilayer phase with a transition temperature of 28/sup 0/C, and evidence is presented indicating that the gramicidin is in the channel conformation. An estimate of the disorder in the alignment of the bilayers parallel with the glass plates used to align the bilayers can be made from the asymmetry of the nuclear magnetic resonances (NMR). Such an analysis indicates a maximal range of disorder of +-3/sup 0/. Uniformly /sup 15/N-labeled gramicidin has been biosynthesized by Bacillus brevis grown in a media containing /sup 15/N-labeled Escherichia coli cells as the only nitrogen source. When prepared with labeled gramicidin, the oriented samples result in high-resolution /sup 15/N NMR spectra showing 12 resonances for the 20 nitrogen sites of the polypeptide. The frequency of the three major multiple resonance peaks has been interpreted to yield the approximate orientation of the N-H bonds in the peptide linkages with respect to the magnetic field. The bond orientations are only partially consistent with the extant structural models of gramicidin.

• Research Organization: Florida State Univ., Tallahassee
• OSTI ID: 5513127
• Journal Information: Biochemistry; (United States), Vol. 26:21
• Country of Publication: United States
• Language: English

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MEMBRANES
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NITROGEN 15
PHOSPHOLIPIDS
BACTERIA
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ORGANIC PHOSPHORUS COMPOUNDS
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