P-component of amyloid. Isolation from human serum by affinity chromatography.

Human amyloid P-component was isolated from plasma by affinity chromatography utilizing antiserum to tissue P-component coupled to Sepharose 4B. Characterization and comparison of the isolated P-component proteins from tissue and plasma demonstrated immunologic identity and identical RF values of polyacrylamide disk gel electrophoresis. Amino acid analyses of P-components from two individual plasmas were comparable, but some variations from tissue P-component were noted. Attempts to perform amino acid sequencing on the plasma protein were unsuccessful. Electron microscopic studies revealed that the plasma P-component had a pentagonal ultrastructure identical to the tissue P-component. These studies compared similarities of tissue and plasma P-components and revealed the unique pentagonal ultrastructure of the plasma protein.