Effect of different solvent systems on the aggregation and conformation of S‐carboxymethyl bovine serum albumin

The aggregation properties of S ‐carboxymethyl bovine serum albumin (SCM‐BSA) have been shown to be greatly influenced by the presence of thioglycollide esters in the thioglycollic acid used as a reducing medium. Pure thioglycollic acid gives a product which is aggregated at both pH 7 and 9. Disaggregation may be effected by sodium dodecyl sulfate, by covalently linking groups on to the molecule in order to increase the net negative charge, and solvents such as 8 M urea, 14 M formamide, 11.5 M acetic acid, formic acid, and 2‐chloroethanol. The mechanisms underlying disaggregation in these widely differing solvents are discussed. The results confirm previous findings of a single polypeptide chain in serum albumin. The optical rotatory dispersion of BSA and SCM‐BSA have been compared in a variety of solvents. It has been shown that the disulfide crosslinks in BSA are not the limiting factor to α‐helix formation.