Biological activity of monomeric Sendai virus HN glycoprotein Free

Two HN glycoproteins of different molecular size were isolated from egg-grown Sendai virus by ion-exchange chromatography on DEAE-Sepharose CL-6B, and gel filtration on Sephadex G-200 at pH 7.2. The larger HN glycoprotein showed both hemagglutinating and neuraminidase activities, whereas the smaller one possessed only the neuraminidase activity. Analysis of their molecular weights showed that the larger HN glycoprotein is a homodimeric molecule of the smaller one. These observations suggest that multi- or divalent binding-sites are required for the expression of hemagglutinating activity and that the monomeric HN molecule itself possesses the enzyme activity.