Isolation and characterization of two major serum proteins from the dogfish, Mustelus canis, C-reactive protein and amyloid P component.
Two major serum components from the dogfish, Mustelus canis, have been isolated using affinity chromatography. Both proteins bind to an AH-Sepharose 4B-phosphorylcholine affinity matrix in the presence of Ca2+ and are eluted from the column by EDTA. Upon readdition of Ca2+ to the eluted proteins, the two proteins can be separated by passage through a column of Sepharose CL-4B. The first protein, C-reactive protein, passes through the Sepharose CL-4B column in the presence of Ca2+ whereas the second protein, serum amyloid P component, remains bound. The serum amyloid P component is then eluted from the Sepharose CL-4B in pure form by EDTA. The dogfish C-reactive protein isolated by the phosphorylcholine affinity matrix precipitates with pneumococcal C-polysaccharide and with a synthetic derivative of bovine serum albumin to which phosphorylcholine is covalently attached. The precipitation is inhibited by either EDTA or by phosphorylcholine. Dogfish C-reactive protein has a molecular weight of approximately 250,000 with dimeric subunits of Mr = 50,000. Upon addition of beta-mercaptoethanol these dimeric subunits dissociate to two identical monomeric subunits of Mr = 25,000. The protein cross-reacts immunologically with goat antisera prepared against rabbit C-reactive protein. The dogfish serum amyloid P component has a molecular weight of at least 250,000 with monomeric subunits of Mr = 25,000. Cross-reactivity of the amyloid P component with the C-reactive protein could not be shown. However, NH2-terminal sequence analysis of the first 20 amino acids showed some homology. The relationship of dogfish C-reactive protein to the C-reactive proteins in Limulus polyphemus and in rabbits and humans is discussed.
D000595:Amino Acid Sequence; D000682:Amyloid / Q000302:isolation & purification*; D000818:Animals; D002097:C-Reactive Protein / Q000302:isolation & purification*; D004220:Disulfides / Q000032:analysis; D004284:Dogfish / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D007106:Immune Sera; D005779:Immunodiffusion; D008970:Molecular Weight; D011487:Protein Conformation; D000683:Serum Amyloid P-Component; D012754:Sharks / Q000097:blood*
D000682:Amyloid; D004220:Disulfides; D007106:Immune Sera; D000683:Serum Amyloid P-Component; D002097:C-Reactive Protein