Interaction of egg albumin and pepsin.

The interaction between enzymes and their substrates to form intermediate complexes has long been of interest. We have found that when pepsin and egg albumin are mixed in solution at about pH 4 a precipitate forms. The influence of protein and of ion concentrations on the amount of precipitate so formed has been studied. It has been found that the precipitate dissolves at higher ionic concentrations and this has given us the opportunity of applying the light-scattering technique to solutions of the dissolved complex between egg albumin and pepsin. From this study we have been able to calculate the association constant of the two proteins as well as to make a rough estimate of the initial rate of digestion of egg albumin by pepsin at pH 4.0.