Colorimetric protein

If analytical methods are at the heart of biopharmaceutical development and manufacturing, then protein concentration methods are the workhorse assays. A time and motion study of the discovery, development, and manufacture of a protein-based product would probably confirm the most frequently performed assay to be protein concentration. In the 1940s Oliver H. Lowry developed the Lowry method while attempting to detect miniscule amounts of substances in blood. In 1951 his method was published in the Journal of Biological Chemistry. In 1996 the Institute for Scientific Information (ISI) reported that this article had been cited almost a quarter of a million times, making it the most cited research article in history. This statistic reveals the ubiquity of protein measurement assays and the resilience of an assay developed over 60 years ago. The Lowry method remains one of the most popular colorimetric protein assays in biopharmaceutical development, although many alternative assays now exist. 

The phospholipid concentration in a (proteo)liposome suspension can be determined by phosphorus analysis (73) and the protein concentration by automated amino acid analysis or by a calibrated colorimetric protein assay... 

Guo, H., et al. (2005) Development of a low density colorimetric protein array for cardiac troponin I detection. J Nanosci Nanotechnol. 5,2161-6. 

J.S. An and W.W. Carmichael, Use of a colorimetric protein phosphatase inhibition assay and enzyme-linked immunosorbent assay for the study of microcystins and nodularins, Toxicon, 32 (1994) 1495-1507. 

C.J. Ward, K.A. Beattie, E.Y.C. Lee and G.A. Codd, Colorimetric protein phosphatase inhibition assay of laboratory strains and natural blooms of cyanobacteria comparisons with high-performance liquid chromatography analysis for microcystins, FEMS Microbiol. Lett., 153 (1997) 465-473. 

Colorimetric protein assay (e.g., Folin-Lowry) Chromatography... 

The membrane concentration is measured using a colorimetric protein determination assay such as those supplied by Bio-Rad or Pierce. 

Skehan, P. et al. 1989. Evaluation of colorimetric protein and biomass stains for assaying drug effects upon human tumor cell lines. Proc. Amer. Assoc. Cancer Res. 30, 612-616. 

Silverman m report ed that several penicillins, including phenoxymethyl penicillin, interfere with the Folin colorimetric protein determination. Since penicillin V gives a pronounced color formation in the absence of protein, it might be possible to use this reaction for its determination. 

Liu, X., Gonzalez, M.G., Niessner, R., Haisch, C., 2012. Strong size-dependent photoacoustic effect on gold nanoparticles a sensitive tool for aggregation-based colorimetric protein detection. Anal. Methods 4, 309—311. 

In the original procedure, soluble zein is assayed by the technique of Kjeldahl [17]. This step has been simplified (Paye, unpublished data) by using a colorimetric protein assay independent of the presence of surfactant, the Bicinchoninic Acid (BCA) protein assay [18]. Correlation between BCA and Kjeldahl assays is shown in Fig. 1. 

TABLE 3 Common Colorimetric Protein Quantitation Assays... 

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