Chromatography of Proteins on Dipolar Ion Adsorbants

Abstract

ROUTINE chromatography of proteins was made possible by the introduction of cellulose ion-exchangers¹. Protein chromatography on ion-exchangers is technically simple but theoretically complex, there being no quantitative theory to act as a guide for experimentation. Proteins are usually unilaterally distributed between the ion-exchange matrix and the surrounding liquid. They are either quantitatively adsorbed (K_d = ∞ : R_F = 0) or not at all (K_d = 0 : R_F = 1)². Finite distribution coefficients are seldom obtained and only in well specified conditions. Gradient elution³ is used to make the separation of proteins on ion-exchangers practicable, where the distribution coefficients shift from zero to infinity or vice versa in a concentration interval too narrow to be otherwise adjusted. On the other hand, calculation of the shape and position of the gradient effluent is difficult with present ion-exchange systems, for the gradient is altered continuously during passage through the bed.