title: [Characterization of the subunits of botulinum neurotoxin type A].
abstract: A comparative amino acid analysis of botulinum neurotoxin type A and its subunits has been carried out. The heavy and light chains of neurotoxin have the same ratios of polar and non-polar amino acids (1.3:1), the amount of tryptophan residues in the heavy chain is 4 times as much as that in the light chain, and the number of SH-groups exceeds that in the light chains 2-fold. In neurotoxin, two N-terminal amino acid residues--alanine and leucine--were identified. Alanine was found to be the N-terminus of the heavy chain. The fluorescence spectra of neurotoxin subunits indicate differences in the conformational state of the polypeptide chains. The antigenic non-identity of botulinum neurotoxin A subunits suggests the presence in the neurotoxin molecule of at least two antigenic determinants, corresponding to the heavy and light chains.
mesh_terms: D000409:Alanine / Q000032:analysis; D000596:Amino Acids / Q000302:isolation & purification*; D001905:Botulinum Toxins / Q000302:isolation & purification*; D002852:Chromatography, Ion Exchange; D003014:Clostridium botulinum; D007930:Leucine / Q000032:analysis; D010446:Peptide Fragments; D011487:Protein Conformation; D014364:Tryptophan / Q000032:analysis
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D014364:Tryptophan; D001905:Botulinum Toxins; D007930:Leucine; D000409:Alanine
vernacular_title: Kharakteristika sub"edinits botulinicheskogo neĭrotoksina tipa A.