Measurement of the diffusion coefficient in the concentrated phases of the soap-water system by nuclear magnetic resonance.

Abstract

A MEASUREMENT of the lateral diffusion coefficient of spin labels in lecithin bilayers has been reported by McConnell et al.1. This diffusion is found to be rapid, the consequences of which, in terms of the structure of biological membranes, cannot be overlooked. Here we report the result of nuclear magnetic resonance measurements on the diffusion coefficient in the concentrated phases of the potassium laurate–heavy water system. Our results strengthen the theory that diffusion in lipid water systems is rapid, magnetic resonance measurements have the advantage that it is the diffusion of the constituent molecule itself that is being observed and not the diffusion of an added “impurity” as is the case with spin fabel experiments.