An Unusually Large (83 Amino Acid Residues) Amyloid Fibril Protein AA from a Patient with Waldenström's Macroglobulinaemia and Amyloidosis

Abstract

Amino acid sequence studies of a human amyloid fibril protein AA derived from a patient with Waldenstrom''s macroglobulinemia revealed 83 residues. This protein AA was larger than, but otherwise very similar to, other human AA proteins studied by complete sequencing. Two amino acids were in position 52 (Val/Ala) and in position 53 (Trp/Arg), strongly suggesting a polymorphism of AA proteins. Immunologic studies showed the antigenic determinant(s) reacting with antiprotein AA were located between positions 25 and 76 of the 3rd CNB cleavage fragment of the protein.