STRUCTURAL STUDIES ON THE SUCCINYLATED BOVINE SERUM ALBUMIN

An analysis of succinylated bovine serum albumin showed that all of the 62 α‐amino groups of lysine residues, 13 hydroxyamino acid residues and 12 tyrosin residues were succinylated, but the succinylated tyrosines were later deacylated. Structural properties of the modified protein have been studied with circular dichroism and sedimentation velocity. At neutral pH (pH 7.60) and in a salt‐free aqueous solution the modified protein is in an expanded form and its helical content is only 30% of that of unmodified protein. The increase of ionic strength restores the original conformation of the protein, whereas the increase of pH further disorganizes the structure of the protein. The results suggest that the electrostatic force alone is responsible for the compact structure of the protein molecule. The same mechanism is believed to underlie the effect of H3O+ and the effect of succinylation of side chain groups on the conformation of bovine serum albumin.