The binding of exogenously added neuraminidase to cells and tissues in culture

Abstract

When neuraminidase-treated cells or tissues and untreated cells or tissues were washed thoroughly and incubated with [ 3H]glucosamine, the culture medium from the neuraminidase-treated cells and tissues contained at least 1.5 times the amount of free sialic acid as that from untreated cells and tissues. When neuraminidase-treated and control cells were incubated with neuramin-lactose, a substrate for neuraminidase, it was cleaved only in the presence of neuraminidase-treated cells. Increased synthesis of sialic acid after neuraminidase treatment cannot explain both sets of data. It appears that neuraminidase is bound at the cell surface, from which it cannot be removed by washing, and is active there in cleaving newly synthesized sialic acid from polysaccharide and/or glycoprotein.