Native and Regenerated Bovine Albumin

1. The effects of regeneration of whole bovine albumin on antigenic activity and serological specificity were determined by precipitin measurements on rabbit antisera to (1) native whole albumin, (2) albumin regenerated from 8 M urea, and (3) albumin regenerated from 8 M guanidine hydrochloride. 2. While numerically the mean antibody response to these three antigens was found to decrease in the order named, only the difference in antigenic activity between native and guanidine hydrochloride-regenerated albumin was statistically significant. Native, crystalline, carbohydrate-free albumin (crystalbumin) was considerably less antigenic than native whole bovine albumin, its activity being comparable to, if not less than, that observed for guanidine hydrochloride-regenerated whole albumin. 3. All four antigens were immunologically equivalent. 4. The antigenic activity of these proteins is discussed in terms of protein structure and carbohydrate content.