Orientation dependence of NMR relaxation time, T-1 rho, in lipid bilayers

The orientation dependence of the low frequency NMR relaxation time, T-1 rh o, of protons in aligned phospholipid bilayers was measured using C-13 cros s polarisation and direct proton experiments. The contribution of intra- an d inter-molecular interactions to proton T-1 rho was determined by using di myristoyl phosphatidylcholine (DMPC) with one hydrocarbon chain deuterated and dispersed in perdeuterated DMPC. The results indicated that intramolecu lar motions on the kHz timescale were the major cause of T-1 rho relaxation in phospholipid bilayers. (C) 2000 Elsevier Science Ireland Ltd. All right s reserved.