title: Complete amino acid sequence of Shigella toxin B-chain. A novel polypeptide containing 69 amino acids and one disulfide bridge.
abstract: The complete amino acid sequence of the B-chain of Shigella toxin has been determined using both liquid- and gas-phase sequenators. It reveals a 69-amino acid peptide with a single disulfide bridge, predicting a subunit molecular weight of 7691. No Asn-X-Ser(Thr) sequence was found, confirming the absence of potential N-glycosylation sites. A computer data bank search using a mutation data matrix did not detect any similarity greater than 30% with known sequences to date, indicating a novel primary structure. However, some distant homology with the 103-residue B-chain of cholera and Escherichia coli enterotoxins was revealed. Hydropathy, fractional exposure, and Chou and Fasman calculations all point to an ordered structure with a hydrophobic core spanning residues 36-52 and a hydrophilic domain between residues 10 and 20, the latter probably representing the most antigenic domain.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001427:Bacterial Toxins / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis*; D022603:Shiga Toxins
chemical_list: D000596:Amino Acids; D001427:Bacterial Toxins; D010446:Peptide Fragments; D022603:Shiga Toxins