Diffusion in rigid bilayer membranes. Use of combined multiple pulse and multiple pulse gradient techniques in nuclear magnetic resonance
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Combined NMR multiple pulse homonuclear decoupling and multiple pulse gradient techniques have been used to determine the self-diffusion coefficients at 25/sup 0/C of the phospholipids in the L/sub ..beta..'/(gel) phase of L-..cap alpha..-dipalmitoylphosphatidylcholine in a 15% (w/w) D/sub 2/O model membrane and of potassium oleate in a 30% (w/w) D/sub 2/O lamellar phase (above the phase transition). The values found, 1.6 x 10/sup -10/ and 1.3 x 10/sup -8/cm/sup 2/S/sup -1/, respectively, are considered in reasonable agreement with values obtained by other investigators using fluorescence photobleaching recovery. The technique has the advantage that it monitors lipid protons and hence avoids possible complications of added probes. The use and limitations of the method are discussed, and the values found for diffusion are compared with those determined or estimated by other methods.