Interference in the Coomassie Brilliant Blue and Pyrogallol Red protein dye-binding assays is increased by the addition of sodium dodecyl sulfate to the dye reagents.

We have investigated the effect of sodium dodecyl sulfate (SDS) upon the response of the Coomassie Brilliant Blue (CBB) and Pyrogallol Red-molybdate (PRM) protein dye-binding assays to interference from aminoglycosides, ampholytes, detergents, phenothiazines, reducing agents, and miscellaneous substances previously reported to interfere with the assays. The CBB assay was less prone to interference than the PRM assay but gave positive interference with the detergents and the phenothiazines and negative interference with dextran sulfate. The PRM assay gave positive interference with the aminoglycosides, ampholytes, and phenothiazines and negative interference with SDS, citric acid, dextran sulfate, EDTA, oxalic acid, and tartaric acid. The level of interference varied in the presence of different proteins (albumin, gamma globulin, alpha1-acid glycoprotein, or lysozyme) and increased when SDS was added to the dye reagents.