Hydrazinoacridine staining of proteins and glycoproteins in polyacrylamide gels

The histochemical method for staining polyaldehydes in tissue sections with p-hydrazinoacridine has been adapted for use in polyacrylamide gels. While staining of histological preparations was reported to be specific for polyaldehydes and independent of bisulfite, both glycoproteins (β chain of haptoglobin) and nonglycoproteins (lysozyme and α chain of haptoglobin) were stained following periodate oxidation, and satisfactory results were highly dependent on the presence of bisulfite. Hydrazinoacridine staining of periodate-treated gels produced an extremely sensitive fluorescent labeling of the haptoglobin β chain and also stained haptoglobin α chain and lysozyme. The proteins could be visualized under visible light as yellow bands which were scanned spectrophotometrically at 440 nm. The β chain of haptoglobin could be subjectively distinguished from the nonglycoproteins both by differential intensity of staining with hydrazinoacridine and Coomassie brilliant blue and by the yellow nature of the fluorescence. The sensitivity of hydrazinoacridine staining of the β chain of haptoglobin compared favorably to that of the commonly used periodic acid-Schiff staining procedures and provided the advantage that nonglycoproteins in complex mixtures could be localized in the gels.