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Amino acid sequence of a κ Bence Jones protein from a case of primary amyloidosis

par Putnam, Frank F.W.;Whitley, Edward E.J.;Paul, Claudine ;Davidson, Jeffrey J.N.
Référence Biochemistry, 12, 19, page (3763-3780)
Publication Publié, 1973

Article révisé par les pairs

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Résumé :

Amino acid sequence analysis has been done on a κ Bence Jones protein (Tew) from a case of primary amyloidosis with the objective of determining the sequence of the variable region. Twenty-two tryptic peptides accounting for 182 residues were isolated and were completely or partially sequenced. Chymotryptic digestion yielded 32 peptides which supplied many overlaps. Sequenator analysis was performed for the first 42 residues of the amino terminus. From the combined data the sequence of the variable region (residues 1-108) was deduced. The composition, partial sequence data, and alignment of the peptides of the constant region (residues 109-214) correspond exactly to the sequence established for human κ light chains of the same allotype. The V region includes five extra residues (30a-30e) and is characteristic of the κII subgroup. A computer analysis of the sequence of the Tew Bence Jones protein in comparison with other human κ light chains was undertaken to establish quantitative criteria for subgroup classification. In terms of minimum nucleotide mutations the Tew protein differs from other subgroup κII proteins by an average of only 0.2 base/amino acid residue position, whereas other human κ chains differ from Tew by an average of 0.4-0.6 base/position. The Bence Jones protein and the tissue amyloid protein from this patient appear to be identical in primary structure as indicated by identity in the amino-terminal sequence for 27 residues and similarity in peptide maps, amino acid composition, and other properties.