Endo-ñ-sialidase (, endo-N-acylneuraminidase, endoneuraminidase, endo-N-acetylneuraminidase, poly(ñ-2,8-sialosyl) endo-N-acetylneuraminidase, poly(ñ-2,8-sialoside) ñ-2,8-sialosylhydrolase, endosialidase, endo-N) is an enzyme with systematic name polysialoside (2âÂÂ8)-ñ-sialosylhydrolase. It catalyses the following chemical reaction: