Solid phase lactoperoxidase radioiodination of microgram quantities of protein mixtures for electrophoretic analysis.

A technique for iodinating microgram quantities of heterogeneous protein mixtures, permitting the visualization of individual polypeptide species following electrophoretic separation, has been developed. Specific activities between 1 and 3 × 10⁵ cpm/μg protein are routinely attained with samples as small as 0.5 μg protein. Banding profiles obtained by radioautography are comparable to those determined by Coomassie blue staining; however, 100-fold less material is needed. The presence of carrier molecules such as polyglutamic acid does not interfere with either iodination or electrophoresis in amounts as high as 1 mg.