A MICROMETHOD FOR PROTEIN ASSAY USING A LIGHT-MICROSCOPE

A micromethod which utilizes a protein-dye binding reaction on an acet ate membrane and a light microscope with an automatic exposure instrum ent has been developed for measuring small amounts of protein from lim ited biological materials. After discoidal cellulose acetate membranes (2.0 mm diameter), which absorbed 0.5 mu l of protein solution contai ning 0.2-2.0 mu g of protein, were stained with Coomassie Brilliant Bl ue G-250, they were examined by a light microscope with an automatic e xposure instrument. A linear relation was confirmed between the intens ity of dye binding to protein and exposure time under specific optical conditions.