Quantification of Proteins on Polyacrylamide Gels (Nonradioactive)

Abstract

It is frequently necessary in biochemical experiments to quantify proteins. There are various methods for estimation of the concentration of total protein in a sample, such as total amino acid analysis, the Biuret reaction, and the Lowry method [see ref. (1)], but these do not allow quantification of one protein in a mixture of several. This may be done by chromatography and estimation of the content of the appropriate peak in the elution profile by virtue of its absorption of light at, say, 220 nm. However, it is usually quicker, easier, and more economical to quantify proteins that have been separated from each other on a polyacrylamide gel. This is done by scanning the gel and by densitometry of the stained bands on it. Microgram quantities of protein may be quantified in this way. The method described below for quantitative staining uses Procion Navy MXRB and is suitable for proteins on acid/urea or SDS polyacrylamide gels (see Chapters 6 to 8).