ASSAY OF PROTEINS IN PRESENCE OF INTERFERING MATERIALS

The Lowry protein assay is a sensitive but highly nonspecific procedure. The standard Lowry protein assay was modified, so that protein can be assayed in the presence of interfering chemicals. The method is based on the observation that in the presence of 125 .mu.g/ml of Na-deoxycholate, bovine serum albumin (5-50 .mu.g) is reproducibly precipitated (90-104%) by 6% trichloroacetic acid. Interference by sucrose, glycerol, Tris-HCl, Tricine and EDTA can be eliminated. Protein samples containing carrier ampholytes can also be assayed provided their NaCl concentration is adjusted to 1 M.