QUANTITATION OF ELECTROPHORETICALLY SEPARATED PROTEINS IN THE SUBMICROGRAM RANGE BY DYE ELUTION

A new method for the fast, reliable and reproducible submicrogram quan titation of proteins separated by different electrophoretic techniques is presented. The method is based on a modified sensitive staining te chnique using Coomassie Brilliant Blue G-250 in colloidal solution com bined with an optimized elution procedure of the bound dye in a 3% w/v solution of sodium dodecyl sulfate followed by photometric determinat ion of dye concentration in the eluate. In addition a new method is pr ovided for background correction, even suitable for gels showing stron g background staining. The staining procedure allows the detection of 20 ng depending on the nature of the protein and the separation techni que used. Quantitation is linear at least in the range from 50 ng to 1 0 mu g and highly reproducible even under non-optimized conditions. Th e presented method can be applied to sodium dodecyl sulfate-electropho resis, isoelectric focusing and two-dimensional electrophoresis.