Influence of solvent conditions on refolding of bovine serum albumin.

The effect of solvent conditions on the refolding of bovine serum albumin was studied. The rate and extent of refolding was affected by the type of monovalent salt used in the medium. While NaCl and NaBr promoted refolding, NaClO4 and NaSCN decreased the rate and extent of refolding at 0.2 M concentration. In this respect the relative order in which various anions influenced the refolding process followed the lyotropic series Cl-, Br-, I-, ClO4-, SCN-. Urea exhibited two opposite effects on the refolding of albumin: whereas at low concentrations urea increased the extent of refolding, at concentrations above 2.0 M the rate and extent of refolding were dramatically decreased. Addition of ethanol to the medium greatly decreased the refolding even at concentrations as low as 4% (v/v). The effects of these various additives on the refolding behavior of serum albumin is interpreted in terms of subtle changes in the structure of water. It is also shown that, while such changes in the solvent structure affected the rate and extent of refolding, they did not affect the pathway of refolding.