A simple method for the purification of commercial neuraminidase preparations free from proteases

A simple method is described for the further purification of commercially prepared neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18) (ex Clostridium perfringens filtrate). A single-step ion-exchange chromatography process renders the enzyme free from proteolytic enzymes and much contaminating protein. Consequently when 125I-labelled proteins, such as fibrinogen, casein, caeruloplasmin, are used as substrates, no proteolytic activity is observed. In contrast, the commercial sample is shown to cleave trichloroacetic acid-soluble 125I-labelled peptides from these three proteins. In addition the purified neuraminidase preparation is subject to both polyacrylamide gel electrophoresis and Sephadex gel filtration under various conditions. Heat stability studies show the enzyme to retain approx. 28% activity after 3 h at 58 °C.