Structural characterization of kappa II Inc, a new amyloid immunoglobulin.
Light chain Inc, obtained from a patient with amyloid arthropathy, has an Mr of 23,550 and consists of 219 amino acid residues. The complete primary structure of its variable domain has been determined by sequence analysis of the corresponding tryptic peptides, aligned by fragments derived from cyanogen bromide digestion, and by partially sequencing the intact protein. Although closely related to protein of the V kappa II subgroup, light chain Inc differs from its counterpart by the replacement of some invariant residues in its variable domain. By comparing its sequence with that of the nonamyloid kappa II Nim, a different distribution of some polar and apolar amino acid residues through the molecule is evidenced. A computer graphic analysis shows that some of the replaced amino acid residues cannot be readily accommodated in the known three-dimensional structure of the immunoglobulin light chains.
Ferri
G
G
Department of Biochemistry, Scientific Institute, San Matteo, University of Pavia, Italy.
Stoppini
M
M
Iadarola
P
P
Bellotti
V
V
Merlini
G
G
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000682:Amyloid / Q000276:immunology*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin; D003488:Cyanogen Bromide; D005260:Female; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000652:urine; D007592:Joint Diseases / Q000276:immunology; D046911:Macromolecular Substances; D008875:Middle Aged; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
D000596:Amino Acids; D000682:Amyloid; D007145:Immunoglobulin kappa-Chains; D046911:Macromolecular Substances; D010446:Peptide Fragments; D002918:Chymotrypsin; D014357:Trypsin; D003488:Cyanogen Bromide