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Spanning or Looping? The Order and Conformation of Bipolar Phospholipids in Lipid Membranes Using 2 H NMR Spectroscopy
Author(s) -
Cuccia L. A.,
Morin F.,
Beck A.,
Hébert N.,
Just G.,
Lennox R. B.
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20001201)6:23<4379::aid-chem4379>3.0.co;2-m
Subject(s) - nuclear magnetic resonance spectroscopy , membrane , spectroscopy , order (exchange) , chemistry , materials science , nuclear magnetic resonance , stereochemistry , physics , biochemistry , finance , quantum mechanics , economics
Solid‐state 2 H NMR spectroscopy was used to study and characterize the conformation and order of bolaform lipid membranes. A series of 2 H‐labeled bolaform phosphatidylcholines has been synthesized and their properties compared to a [D 4 ]dimyristoylphosphatidylcholine (DMPC) and a [D 8 ]‐32 macrocyclic phosphatidylcholine. 31 P NMR measurements establish that the aqueous dispersions of these lipids adopt lamellar phases. Computational dePakeing was used to extract the spectrum of the oriented system from spectra consisting of a superposition of randomly oriented domains in an unoriented sample. A large (>90 %) and constant value for the normalized segmental order parameter ( S mol ) was observed for all positions along the diacyl chain of the bolaform lipids and only a small population (<10 %) of a less ordered conformer was observed. The less ordered conformer is assigned to the looping conformation on the basis of comparison with the deuterated macrocyclic phospholipid which has an enforced loop in its diacyl chain. The predominant population(>90 %) of the bolaform lipids is assigned to a highly ordered, spanning conformer.