Amyloid β2-microglobulin is modified with Nε-(carboxymethyl)lysine in dialysis-related amyloidosis

1 Amyloid β 2 -microglobulin is modified with N e -(carboxymethyl)lysine in dialysis-related amyloidosis. Recent work from this laboratory revealed that advanced glycation end product was localized to amyloid deposits in patients with dialysis-related amyloidosis by immunohistochemistry using a monoclonal antibody to advanced glycation end product. To elucidate the epitope of the antibody, N α -p-tosyl-L-lysine-methyl ester was incubated with glucose in vitro , and then a compound reactive to the antibody was purified from the incubate by buthanol extraction, XAD-2 column chromatography, and high-performance liquid chromatography while the reactivity was examined by enzyme linked immunosorbent assay. The purified compound was identified as N e -(carboxymethyl)-N α -p-tosyl-L-lysine-methyl ester by using secondary ion mass spectrometry, and 1 H- and 13 C-nuclear magnetic resonance spectroscopy. The epitope of the antibody was identified as -CH 2 -NH-CH 2 -COOH by enzyme-linked immunosorbent assay of compounds with structures similar to N e -(carboxymethyl)lysine. Immunochemical study using the antibody demonstrated the presence of N e -(carboxymethyl)lysine in the β 2 -microglobulin dimer (molecular weight 23929) isolated from the synovium amyloid of a hemodialysis patient with dialysis-related amyloidosis. In conclusion, amyloid β 2 -microglobulin is modified with N e -(carboxymethyl)lysine in dialysis-related amyloidosis.