Fluorescent staining of sialidases in polyacrylamide gel electrophoresis and ultrathin-layer isoelectric focusing.

Polyacrylamide gels were stained with the sialidase substrate 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid showing the activity of Vibrio cholerae and Clostridium sordellii sialidases in the gels after electrophoresis. With this fluorogenic method minimum sialidase activities of 5 microU could be determined. The sensitivity of this staining is about 10,000-fold higher compared to protein-staining with Coomassie brilliant blue. For the visualization of other proteins than sialidases the specific sialidase staining could be followed by a protein-staining method in the same gel.