[³H]dansyl chloride: A useful reagent for the quantitation and molecular weight determination of nanogram amounts of protein

A simple, rapid, and reproducible method is described for the quantitation of submicrogram amounts of protein. This method is based upon the reaction of ³H-labeled 1-dimethylaminonaphthalene-5-sulfonyl chloride ([³H]dansyl chloride) with protein under denaturing conditions. As little as 50 ng of protein can be detected under the experimental conditions described, and the assay is linear over the range 50 to 5000 ng of protein. Furthermore, this method has been used for the electrophoretic determination of molecular weights of proteins available in submicrogram amounts.