Applications of Electrophoresis in studying New Antibiotics

Abstract

THE application of paper electrophoresis to the study of new antibiotics¹ has been in use at these laboratories for some time. Our technique consists of applying spots of culture fluid, or a concentrate of it, to paper strips soaked in buffer, and subjecting the strips to electrophoresis by the technique of Kunkel and Tiselius². Spots of chloromycetin are applied to the paper on each side of the spot of unknown antibiotic as a control for electro-osmosis. After migration, the position of the antibiotic is revealed by the microbiological technique as usual in paper chromatography of antibiotics³. Thus it is possible to determine whether unknown antibiotics in culture fluids are acidic, basic or amphoteric, and to obtain an approximate measure of their isoelectric point as a guide to subsequent purification procedures. The migration of an unknown antibiotic 179, relative to chloromycetin, to the cathode at pH 3 and pH 8, with lessened mobility at pH 8, indicates a basic substance with an isoelectric point greater than pH 8, as illustrated in the accompanying photograph.