title: Disulfide bonds of purothionine, a lethal toxin for yeasts.
abstract: Purothionin isolated from commercial wheat flour contained several components and two of them (A-I and A-II) were isolated in pure form by CM-52 column chromatography. Each component contained 45 amino acid residues with a 4 disulfide bonds. Purothionin A-II was digested with trypsin and thermolysin to isolate cystine peptides. These were separated and purified by chromatography on an SP-Sephadex column, and paper electrophoresis and chromatography. A peptide containing a -Cys-Cys- sequence was hydrolyzed with 10 N sulfuric acid. Amino acid compositions and partial sequence studies of the cystine peptides and their performic acid-oxidized peptides revealed the positions of all 4 disulfide bonds in purothionin A-II. They were formed between residues 3 and 39, 4 and 31, 12 and 29, and 16 and 25. The results of a partial study of purothionin A-I are also presented.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D004220:Disulfides / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis; D010940:Plant Proteins / Q000494:pharmacology; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D014118:Toxins, Biological / Q000494:pharmacology; D014908:Triticum
chemical_list: D000596:Amino Acids; D004220:Disulfides; D010446:Peptide Fragments; D010940:Plant Proteins; D014118:Toxins, Biological