High-resolution 13C nuclear magnetic resonance studies of small unilamellar vesicles containing glycophorin A.

Glycophorin A, the major sialoglycoprotein of the human erythrocyte membrane, has been incorporated in small unilamellar vesicles containing phosphatidylcholine and phosphatidylethanolamine in varying proportions. Hydrocarbon chains of these two lipids have been selectively enriched with 13C and 13C-NMR spin relaxation parameters have been monitored in the presence and absence of protein. Perturbations to 13C line-widths and spin-lattice relaxation times are found to be small and consistent with relatively weak interactions. The perturbations, though small, show some specificity. The carbonyl carbons in both phosphatidylcholine and phosphatidylethanolamine are broadened, but in addition the olefinic carbons in phosphatidylethanolamine are broadened.