One-step procedure for the purification of goldfish (Carrasius auratus) and carp (Cyprinus carpio, L.) serum immunoglobulin by precipitation with 9% polyethylene glycol 6000

Goldfish and carp IgM was precipitated from their sera in the presence of 9 % polyethylene glycol 6000. The precipitate, when solubilized in a quantity of phosphate buffer equal to the initial volume of the serum, showed an EL ISA antibody activity almost equivalent to that of the initial serum. This solution gave a single IgM electrophoretic band in 3.5% SDS-PAGE under non- reducing conditions. However, neither residual ELISA antibody activity nor the presence of IgM electrophoretic bands could be detected in the supernat ant after removal of the precipitate by centrifugation. SDS-PAGE of IgMs fr om the above species, performed under reducing conditions, revealed appropr iate heavy and light chains of 71 and 24-26 kDa that reflect a tetrameric M W of 760-768 kDa in both species. The purity of the polyethylene glycol (PE G) precipitated IgM fraction as evaluated by computerized density analysis was estimated at about 95%.