Nuclear magnetic resonance studies of phospholipid micelles.

The proton magnetic resonance spectrum of DL-a!-lecithin at 100 MHz in CHCJ solvent is reported. An analysis of the spectrum is made. The chemical shifts of the N-(CH& protons and the resonance peak associated with the condensed water molecule showed concentration dependence with the latter showing the more pronounced response. These chemical shift changes are interpreted in terms of micelle formation through intermolecular hydrogen bond formation between lecithin monomers. The chemical shift data are used to calculate the critical micelle concentration of lecithin as well as the number of monomer lecithin units required to form a micelle. The temperature-dependent studies showed a small negative enthalpy change associated with the micelle. The micellar behavior in CHCl, is compared with those in benzene and carbon tetrachloride.