Assay of plant proteins with bicinchoninic acid for high resolution two-dimensional polyacrylamide gel electrophoresis.

A method is described for estimating proteins in the same plant tissue sample that is solubilized for separation by two-dimensional polyacrylamide gel electrophoresis. The method uses a modified bicinchoninic acid (BCA) protein assay procedure and a modified standard urea solubilization buffer to estimate microgram values of unknown protein concentration, in the presence of 9 M urea and 4% Nonidet P-40, from a linear standard curve. A method for a quantitative determination of protein concentration by BCA in a sample containing 9 M urea and 4% Nonidet P-40 is also described. This method is effective for the determination of proteins in minute non-green and green plant tissue, and is especially designed for vegetative and floral shoot apices, and the primordia of inflorescences.