DESORPTION OF PROTEINS FROM THE AIR WATER INTERFACE

Rates of desorption of proteins were measured by the decrease in area at a reference surface pressure of 5 mN m** minus **1 after maintaining monolayers at higher constant pressures for given times. Kinetics followed a t** one-half relation, consistent with a diffusion-controlled process from a subsurface layer of constant concentration. For two proteins studied, beta -lactoglobulin and insulin, initial rates of desorption from mixed monolayers with nondesorbable components were the same as for the pure monolayers. A comparison of five proteins showed that rates of desorption decreased markedly with increasing molecular weight at a given surface pressure. These results should assist in understanding transport processes across interfaces and membranes and competitive adsorption from protein mixtures in processes such as blood clotting.