A nuclear magnetic resonance spectroscopic investigation of the headgroup motions of lysophospholipids in bilayers

Fully hydrated lysophospholipids in both the gel and the liquid crystalline states have been shown to exhibit negative phosphorus chemical shift anisotropies (Δσ) by31P nuclear magnetic resonance (NMR). The magnitude of Δσ for monoacyl lysophospholipids is found to be smaller than that of the corresponding diacyl phosphospholipids in bilayers by about a factor of two. We present evidence to suggest that the reduction in Δσ can be attributed primarily to an additional motional averaging of the lysophospholipid headgroup, and the additional motion can best be explained by rapid rotational motions of the headgroup about the C(1)-C(2) glycerol bond.