title: Pantetheine-linked peptide intermediates in gramicidin S and tyrocidine biosynthesis.
abstract: To study the function of pantetheine in gramicidin S and tyrocidine biosynthesis, pepsin digests of the polymerizing enzymes, of which only the heavy ones contain pantetheine, were analyzed. The digests of gramicidin S enzymes charged with either [(14)C]proline or with D-phenylalanyl-[(14)C]proline, were analyzed by thin-layer chromatography; only the dipeptide showed a derivative associated with pantetheine. Similar results were obtained from the heavy tyrocidine enzyme charged with either [(14)C]asparagine alone or with the pentapeptide D-Phe-Pro-Phe-D-Phe-[(14)C]Asn. Several radioactive products appeared on the thin-layer chromatograms of both these digests; association with pantetheine was found only in the case of the pentapeptide. Exposure of the chromatogram from the pentapeptide-labeled digest to performic acid and development in a second direction separated the peptide from pantetheine, indicating that a nascent peptide was originally linked to the cofactor by a thioester bond. The connection of pantetheine only with peptide residues appears to confirm its role in transpeptidation during peptide chain growth.
mesh_terms: D001216:Asparagine / Q000032:analysis; D002219:Carbamates / Q000494:pharmacology; D002247:Carbon Isotopes; D002850:Chromatography, Gel; D002855:Chromatography, Thin Layer; D004798:Enzymes; D006885:Hydroxybutyrates / Q000494:pharmacology*; D010434:Pepsin A / Q000494:pharmacology; D010452:Peptide Biosynthesis; D010442:Peptide Chain Initiation, Translational; D010455:Peptides / Q000032:analysis; D010649:Phenylalanine / Q000032:analysis; D011392:Proline / Q000032:analysis; D013438:Sulfhydryl Compounds / Q000494:pharmacology*; D014449:Tyrothricin / Q000096:biosynthesis*
chemical_list: D002219:Carbamates; D002247:Carbon Isotopes; D004798:Enzymes; D006885:Hydroxybutyrates; D010455:Peptides; D013438:Sulfhydryl Compounds; D014449:Tyrothricin; D010649:Phenylalanine; D001216:Asparagine; D011392:Proline; D010434:Pepsin A