[Immunoglobulin-like serum proteins from the ratfish (Callorhynchus callorhynchus) (author's transl)].

Ratfish serum proteins have been fractionated by ammonium sulfate, followed by gel filtration on Sepharose 6B. This experimental procedure yields very pure product, as assayed by inmunoelectrophoresis and rechromatography en Sepharose 6B. Basic polypeptide structural analysis performed by polycrylamide sodium dodecylsulfate gel electrophoresis (PAGE-SDS) shows two polypeptides, having 7.49 X 10(4) daltons and 2.44 X 10(4) daltons, respectively. The hexose content is less than in the similar high molecular weight immunoglobulin heavy chain from the human previously described. This fact could explain the apparent low molecular weight of such polypeptide on PAGE-SDS. The molecular weight determination of the native molecule by protein gel filtration on Sepharose 6B, gives a value of about 9.6 X 10(5) daltons, which is similar in that found for others Chondrichthyes high molecular weight immunoglobulins described before by others.