It has been pointed out that plasma albumin undergoes a transformation between N and F forms depending on pH at a pH region 3.0-5.0(2). Sogami and Foster(8) recently suggested that there might exist a large number of closely related albumin species having slightly different types of tertiary structures.
Each species has its own characteristic pH at which the N-F transformation takes place, and the transformation is extremely sharp being accompanied by a 12 hydrogen transfer. Assuming a Gaussian type distribution of a population of these species, we can properly explain the observed pH dependence of the N-F transformation.
Because of the much lower water solubility of F form and its enhanced solubility in organic solvents (5) , partition chromatography seems to be useful to separate albumin into two subfractions corresponding to N and F forms. Moreover, we can expect that many albumin species might be separated by a pH gradient elution because of their characteristic pH dependences.
Under these considerations, a pH gradient partition chromatography was attempted for plasma albumin.