Peptides: An analytical method for their resolution by polyacrylamide gel electrophoresis applicable to a wide range of sizes and solubilities

Polyacrylamide gel electrophoresis of Fluorescamine-modified peptides is a rapid (90 min), sensitive (<1 nmole), and reproducible method which may be used to resolve peptides without the limitations with respect to molecular size or water solubility found in other analytical systems. Fluorescamine-modified peptides, ranging in size from 3 to 215 amino acids, have been examined in a variety of buffer systems between pH 2.3 and 9.8 and gel concentrations varying between 4% and 16% acrylamide. Similar peptides were examined by high-voltage paper electrophoresis and detected by Fluorescamine. Peptides of low solubility have been examined in the presence of urea. The method reported here was used to resolve small peptides differing in size by a single amino acid, as well as peptides of the same size differing only by a sinle charge. It was successfully employed as a criterion for homogeneity of peptides in the course of purification for amino acid sequence analysis.