Isolation and characterization of amyloid protein AA in the Abyssinian cat

Amyloid fibrils were isolated by extraction in deionized water from the kidneys of an Abyssinian cat with familial renal amyloidosis. The fibrils were suspended in a buffer containing 6 M guanidine hydrochloride and reduced and alkylated using dithiothreitol and iodoacetid acid. The resulting amyloid fibril subunit protein was isolated by chromatography on a column of Sepharose CL6B. It was fragmented using cyanogen bromide, and the resultant peptides were separated by reverse phase high performance liquid chromatography. The protein was characterized by determination of the amino acid sequence of the cyanogen bromide fragments using a Beckman 890C sequencer. The primary structure of this amyloid fibril subunit protein showed strong homology with amyloid protein AA found in man and animals with spontaneous and experimentally induced reactive systemic amyloidosis. This study confirms the reactive nature of familial renal amyloidosis in the Abyssinian cat and suggests that this disease may be a valuable spontaneous animal model for the study of familial Mediterranean fever in man.