title: Primary structure of human J chain: alignment of peptides from chemical and enzymatic hydrolyses.
abstract: The primary structure of the J chain from a human Waldenströms IgM protein has been determined using a combination of automated and conventional Edman degradative procedures. Eighty-five percent of the sequence was established with peptides isolated from tryptic digests of carboxyamidomethylated and citraconylated J chain, many of which were sequenced completely. Alignment of the tryptic fragments was achieved with peptides generated by chymotrypsin and limited acid hydrolyses. The j chain consits of 129 amino acids and a single oligosaccharide structure linked to asparagine at positon 43 of the sequence. The molecular weight, including 7.5% carbohydrate by weight, is 16 422. The location and arrangement of three half-cystines could be deduced from previous studies, whereas the pairing of the remaining five disulfide bonds still needs to be clarified.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D055598:Chemical Phenomena; D002621:Chemistry; D002918:Chymotrypsin; D006801:Humans; D006868:Hydrolysis; D007144:Immunoglobulin J-Chains; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin; D008258:Waldenstrom Macroglobulinemia / Q000276:immunology
chemical_list: D000596:Amino Acids; D007144:Immunoglobulin J-Chains; D010446:Peptide Fragments; D002918:Chymotrypsin; D014357:Trypsin