Neoplastic Alteration of a Membrane‐associated Sialidase of Rat Liver

Rat liver participate fraction contains two types of membrane‐associated and gangliosides‐hydrolyzing sialidase, which have been shown to be identical to two membrane‐associated sialidases of rat brain (I and II) chromatographically, immunologically and in substrate specificity. Chromatography on AH‐Sepharose 4B of the membrane sialidases of rat primary hepatoma induced by 3′‐methyl‐4‐dimethylaminoazobenzene (MeDAB) further revealed that hepatocarcinogenesis induces a marked decrease in sialidase II but no decrease in sialidase I. Using antisera against sialidases I and II of rat brain, immunoprecipitation studies of the solubilized particulate fractions of rat liver and MeDAB‐hepatoma gave results similar to those obtained chromatographically. Using the same immunological technique, sialidase II but not sialidase I was found to be decreased in AH109 A hepatoma and in regenerating and fetal liver.