The protein concentration of crude cell and tissue extracts as estimated by the method of dye binding: Comparison with the lowry method

Abstract The protein concentration of crude extracts from cultured cells and of subcellular fractions from rat tissues has been estimated both by the method of Bradford, involving the binding of Coomassie brilliant blue G-250, and by the procedure of Lowry et al. with the same preparation of bovine serum albumin as a common protein standard. Whereas the method of dye binding yielded significantly lower values than did the Lowry procedure, a consistent quantitative relationship existed between the values obtained by the two techniques. Evidence is provided that this discrepancy does not result from the presence in such complex biological mixtures of a class of small peptides, undetected by the method of dye binding, that react with the Lowry reagents.