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Protein assays Using this web site

Protein Assays

Below is a list of assays for the determination of protein concentration in a solution. This list includes the sensitivity range, volume/amount of sample needed, subjective comments on accuracy and convenience, and major interfering agents. Procedural details, equipment requirements, and references are outlined in the individual assay documents.

The criteria for choice of a protein assay are usually based on convenience, availability of protein for assay, presence or absence of interfering agents, and need for accuracy. For example, the Lowry method is very sensitive but is a two step procedure that requires a minimum of 40 minutes incubation time. The Bradford assay is more sensitive and can be read within 5 minutes, however proteins with low arginine content will be underestimated. Generally, estimates are more accurate for complex mixtures of proteins. Estimates of concentration of pure proteins can be very inaccurate depending on the principle of the assay, unless the same pure protein is used as a standard. Criteria will be discussed in the individual documents.

General Reference: Stoscheck, CM. Quantitation of Protein. Methods in Enzymology 182: 50-69 (1990).

Absorbance assays

Colorimetric assays

Copyright and Intended Use
Created by David R. Caprette (, Rice University 7 Sept 1995
Updated 11 May 2000