NMR Studies of a 13C,15N-Labeled GM4-Lactam Glycolipid at an Oriented Model-Membrane Interface
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- 作者：Brian A. Salvatore ; Ranajeet Ghose ; and James H. Prestegard
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：May 1, 1996
- 年：1996
- 卷：118
- 期：17
- 页码：4001 - 4008
- 全文大小：361K
- 年卷期：v.118,no.17(May 1, 1996)
- ISSN：1520-5126
文摘
Liquid crystal NMR techniques were used to study an isotopicallylabeled lactam analog of gangliosideGM4 in an oriented bilayer system composed ofL-
-dimyristoylphosphatidylcholine (DMPC) and3-((cholamidopropyl)dimethylammonio)-2-hydroxy-1-propanesulfonate (CHAPSO). Thisdiscoidal bilayer system is used to mimic abiological membrane, the natural environment of GM4 andother glycolipids. Residual dipolar couplings(13C-13Cand 15N-13C) and chemical shift anisotropyeffects for the amide 13C and 15N labeled siteswere measured in GM4lactam, using both one- and two-dimensional NMR methods. Thedipolar coupling data were interpreted using atorsional search for preferred geometry about the two elements of theglycosidic bond attaching the headgroup to thebilayer surface. This yielded three independent families ofstructures, all of which were consistent with the dipolarcoupling data. An order matrix analysis was used to compareexperimentally measured changes in chemical shiftsupon orientation to those predicted by chemical shift tensors derivedfrom ab initio calculations. One of thethreefamilies of structures was readily eliminated based on chemical shiftmeasurements, and another was eliminatedbased on energetic considerations, leaving a single structure torepresent the average conformation of the GM4lactamheadgroup at a membrane surface.
-dimyristoylphosphatidylcholine (DMPC) and3-((cholamidopropyl)dimethylammonio)-2-hydroxy-1-propanesulfonate (CHAPSO). Thisdiscoidal bilayer system is used to mimic abiological membrane, the natural environment of GM4 andother glycolipids. Residual dipolar couplings(13C-13Cand 15N-13C) and chemical shift anisotropyeffects for the amide 13C and 15N labeled siteswere measured in GM4lactam, using both one- and two-dimensional NMR methods. Thedipolar coupling data were interpreted using atorsional search for preferred geometry about the two elements of theglycosidic bond attaching the headgroup to thebilayer surface. This yielded three independent families ofstructures, all of which were consistent with the dipolarcoupling data. An order matrix analysis was used to compareexperimentally measured changes in chemical shiftsupon orientation to those predicted by chemical shift tensors derivedfrom ab initio calculations. One of thethreefamilies of structures was readily eliminated based on chemical shiftmeasurements, and another was eliminatedbased on energetic considerations, leaving a single structure torepresent the average conformation of the GM4lactamheadgroup at a membrane surface.