A semi-automated protein assay for cell cultures

A semi-automated modification of the protein determination procedure of O. H. Lowry, N. J. Rosebrough, A. L. Farr, and R. J. Randall (1951, J. Biol. Chem. 193, 265-275) is described. The assay is well suited to the analysis of the protein of adherent cultured cells. The procedure is carried out in 96-well microtest plates on protein solutions of 50 microliter or less, and can detect less than 0.5 micrograms of protein (equivalent to about 10(3) cultured cells). Optical densities are read and printed by an automatic microplate reader capable of processing 96 samples in less than 2 min.