Copurification and separation of beta-galactosidase and sialidase from porcine testis

A soluble sialidase was copurified apparently as an enzyme complex with acid beta-galactosidase from porcine testis. The sialidase exhibited its maximum activity at acidic pH. It was efficiently active towards 4-methylumbelliferyl-alpha-D-N-acetyl-neuraminic acid and sialyllactose, relatively inactive towards glycoproteins, and had little activity towards glycolipids. The complex could be separated by sucrose gradient centrifugation or isoelectric focusing. The separated enzymes had molecular weights about 600,000 for beta-galactosidase and more than about 1,000,000 for sialidase by Sepharose 4B gel filtration. SDS-polyacrylamide gel electrophoresis of the beta-galactosidase showed three protein bands with molecular weights of 63,000, 31,000 and 20,000.