Conformational studies of sphingolipids by NMR spectroscopy. I. Dihydrosphingomyelin

Abstract

The conformational features of dihydrosphingomyelin (DHSM), the major phospholipid of human lens membranes, were investigated by 1H and 31P nuclear magnetic resonance spectroscopy. Several postulates emerge from the observed trends: (a) in partially hydrated samples of DHSM in CDCl3 above 13 mM, at which lipid-lipid interactions prevail, the amide proton is mostly involved in intermolecular H-bonds that link neighboring phospholipids through bridging water molecules. In the absence of water, the NH group is involved in an intramolecular H-bond that restricts the mobility of the phosphate group. (b) In the monomeric form of the lipid molecule, the amide proton of the major conformer is bound intramolecularly with one of the anionic and/or ester oxygens of the phosphate group. A minor conformer may also be present in which the NH proton participates in an intramolecular H-bond linking to the OH group of the sphingoid base. (c) Complete hydration leads to an extension of the head group as water molecules bind to the phosphate and NH groups via H-bonds, thus disrupting the intramolecular H-bonds prevalent at low concentrations.

Sphingomyelin and Cholesterol: From Membrane Biophysics and Rafts to Potential Medical Applications

“…) lipid packing may result from this, and this may be an additional explanation for the higher LD to SO phase transition temperature range of SMs than PCs (Barenholz et al, 1976;Frank et al, 1983). A larger degree of intermolecular hydrogen bonding (Ferguson-Yankey et al, 2000;Talbott et al, 2000), as well as tighter membrane packing and lower membrane permeability are further consequences (Abrahamsson et al, 1977) of an increased mole fraction of SMs in membranes at the expense ofPCs. The presence of 10 mole% enhances the partition coefficient of ethanol into lipid membranes and this effect is related, to a large extent, to the interface region of SMs and is much less affected by the headgroup (Mouritsen et al, 1999).…”

“…In hydrated lipids, the amide proton is involved mostly in an intermolecular H-bond that links adjacent DHSM molecules, while in the absence of water the NH moiety forms an intramolecular H-bond with the phosphate moiety, which restricts the mobility of the latter. In excess water the latter intramolecular H-bond is disrupted, thereby changing the balance in favor of water-mediated intermolecular H-bonding (Ferguson-Yankey et al, 2000).…”

“…in Thompson, 1980, 1999). The phosphate of the phosphocholine headgroup may also be involved in the H bonding with the amide and/or hydroxyl groups at the interface region, and such interaction may restrict the headgroup motion through inter-or intramolecular interactions (Talbott et al, 2000;Ferguson-Yankey et al, 2000). In comparison, PC, through its two acyl ester carbonyls can serve only as hydrogen acceptor (with respect to hydrogen bonds).…”

A DFT study of infrared spectrum of sphingomyelin lipid molecule with calcium cation

“…There are various possible hydrogen bindings among amide, hydroxy, and charged oxygen atoms of phosphate moiety. Besides, the C2 and C3 of sphingosine have different stereochemical conformations; however, 2S,3R (or D-erythro) has been determined by nuclear magnetic resonance (NMR) studies [4,[15][16][17].…”

Ab initio and DFT study of 31P‐NMR chemical shifts of sphingomyelin and dihydrosphingomyelin lipid molecule

“…Infrared (IR) spectroscopy [6] and light scattering [7] were measured to study the effect of the double bond, with relation to calcium concentration. Moreover, they have used NMR spectroscopy for investigating intramolecular and intermolecular hydrogen bondings involved with solvent water molecules [5,9]. Especially in the cataract human lens, the chemical abundance of phospholipids includes DHSM lipids by 31 P-NMR spectroscopy [10].…”