Modified Bovine Serum Albumin—ix. The Effect of Ultraviolet Irradiation on the Immunochemical Properties*†

Summary Changes produced in crystalline bovine serum albumin (BSA) by ultra‐violet irradiation have been investigated by immunochemical techniques. The quantitative precipitin reaction employing anti‐BSA was used to detect protein alteration. Irradiation of BSA progressively caused a shift in the point of maximum precipitation in the direction of higher antigen concentration, broadening of the zone of maximum precipitation, and after sufficient irradiation, a reduction in the total amount of precipitable nitrogen. Although it is known that U.V. light can theoretically rupture any of the bonds present in a protein, no appreciable amounts of dialyzable fragments were formed by irradiation of BSA.