Effect of transmembrane electrical potential and micelle geometry on phospholipid head group conformation

Abstract

Phospholipid head group conformation has been measured in egg phosphatidyl choline vesicles with a transmembrane electrical potential. Using 31P NMR, the proton source of the 31P[ 1H] nuclear Overhauser effect has been determined and the head group conformation shown to be unperturbed by a transmembrane electrical potential near 60 mV. The same technique was used to probe polar head group conformation in lysophosphatidyl choline micelles. The geometric constraints of the micelle structure force the head groups apart, preventing the intermolecular head group interactions found in phosphatidyl choline bilayers.