Effect of oxidative sulfitolysis of disulfide bonds of bovine serum albumin on its structural properties: a physiochemical study.

The effect of S-S bond cleavage of bovine serum albumin (BSA) on some of its structural properties, including solubility, viscosity, and conformation, were investigated. Cleavage of S-S bonds decreased the solubility of serum albumin and also shifted its isoelectric point to lower pH values. S-S bond cleavage resulted in changes in shape and hydrodynamic volume of the protein, increasing the specific viscosity, with cleavage of up to 14 S-S bonds, followed by a decrease with further cleavage. Both UV difference and fluorescence spectral measurements indicated that conformational flexibility increases with S-S bond cleavage. Secondary structure estimations by far UV-CD suggested a gradual decrease in alpha-helical content of the protein with progressive cleavage of its S-S bonds. However, fully S-S bond cleaved protein maintained some alpha-helical structure. Sulfitolysis of the protein also decreased its 1,8-anilino-naphthalene sulfonate-binding ability.