Amyloid-related serum protein SAA from three animal species: comparison with human SAA.

The amyloid-relates serum protein SAA has been isolated by gel filtration in 10% formic acid from three animal species: mink, mouse, rabbit. Sera used in the isolation procedure were obtained from animals in which high concentrations of SAA had been induced by treatment with LPS. The isolated SAA proteins had a subunit size similar to that of human SAA, with m.w. values ranging from 10,000 to 11,700 (estimated by gel filtration in 6 M guanidine-HC1) or 12,400 to 15,000 (estimated by SDS-PAGE). The m.w. studies and amino acid sequence data indicated that SAA and the amyloid fibril protein AA in the mouse, and probably also the mink, are related in the same way as in man, the two proteins having common NH2-terminal amino acid sequences and SAA being extended by 20 to 40 residues at the COOH-terminal end of the molecule.