A method to detect polysialic acid in polymers of 10 or more sialyl residues synthesized in vivo and in vitro.

An immunoaffinity column has been used to detect polysialic acid containing 10 or more sialyl residues. Antibodies specific for colominic acid were purified from horse serum by immobilized colominic acid and were bound to CH-Sepharose-4B. The immunoaffinity column was used to assay the activity of CMP-NeuNAc: poly alpha 2-->8-sialosylsialyltransferase by detecting the products which were synthesized in vitro by an extract from rat brain and CMP-[14C]NeuNAc. In addition, polysialic acid was demonstrated in a fraction of glycoproteins from human neuroblastoma cells, labeled metabolically with [3H]GlcN. The column was further characterized by binding of 3H-colominic acid and by treatment of the bound polymers with endoneuraminidase, specific for the degradation of polysialic acid. The method can be used for rapid detection of polysialic acid synthesized in vivo and in vitro.