Previously, we have reviewed in this journal (Arakawa, T., Kita, Y., Curr. Protein Pept. Sci.,
15, 608-620, 2014) the interaction of arginine with proteins and various applications of this solvent additive
in the area of protein formulations and downstream processes. In this special issue, we expand the
concept of protein-solvent interaction into the analysis of the effects of solvent additives on various column
chromatography, including mixed-mode chromatography. Earlier in our research, we have studied
the interactions of such a variety of solvent additives as sugars, salts, amino acids, polymers and organic
solvents with a variety of proteins, which resulted in mechanistic understanding on their protein stabilization
and precipitation effects, the latter known as Hofmeister series. While such a study was then a
pure academic research, rapid development of genetic engineering technologies and resultant biotechnologies
made it a valuable knowledge in fully utilizing solvent additives in manipulation of protein solution,
including column chromatography.