Conformational studies of sphingolipids by NMR spectroscopy. II. Sphingomyelin

Area of Science:

• Biochemistry
• Biophysics
• Membrane Biology

Background:

• Sphingomyelin (SM) is a key sphingolipid in mammalian cell membranes.
• Understanding sphingolipid interactions is crucial for elucidating membrane structure and function.
• Dihydrosphingomyelin (DHSM) differs from SM by lacking a double bond in its sphingoid base.

Purpose of the Study:

• To investigate the intra- and intermolecular hydrogen bonding in sphingomyelin (SM) and dihydrosphingomyelin (DHSM).
• To compare the hydrogen bonding characteristics between SM and DHSM in monomeric and aggregated states.
• To assess the influence of the sphingoid base double bond on lipid interactions.

Main Methods:

• Proton nuclear magnetic resonance (NMR) spectroscopy.
• 31P nuclear magnetic resonance (NMR) spectroscopy.
• Analysis of spectral data to determine hydrogen bond nature and strength.

Main Results:

• Evidence for an intramolecular hydrogen bond between the sphingosine OH group and the phosphate ester oxygen in SM.
• This intramolecular hydrogen bond is stronger in SM compared to DHSM, indicated by NMR spectral trends.
• At higher concentrations, SM's NH group engages in lipid-water interactions, while intramolecular bonding persists more strongly in SM than DHSM.

Conclusions:

• The presence of the double bond in SM influences the strength and prevalence of intramolecular hydrogen bonds.
• Differences in molecular packing and intermolecular interactions exist between SM and DHSM.
• Hydrogen bonding patterns significantly contribute to the distinct behaviors of SM and DHSM in membrane environments.