Human Serum Cholinesterase as a Sialo‐Protein

Incubation of human serum with sialidase (neuraminidase, receptor destroying enzyme) results in a marked decrease of the mobility of cholinesterase without affecting the enzymatic activity as indicated by the splitting of acetylcholine and butyrylcholine. The results suggest that human serum cholinesterase is an acid glycoprotein containing several sialic acid residues per molecule. In normal serum sialidase could not be detected whereas spinal fluid showed weak sialidase activity. In a single pool of serum from patients a marked sialidase activity was observed.