title: Non-ribosomal biosynthesis of the cyclic octadecapeptide alamethicin.
abstract: The biosynthesis of the cyclic octadecapeptide, alamethicin, in a cell-free system of Trichoderma viride has been investigated. It was shown that nucleic acid- and ribo-some-free extracts of Trichoderma viride could catalyze alamethicin biosynthesis. Puromycin, erythromycin and RNAse did not inhibit this synthesis. The Sephadex G 200 filtrate contains a fraction (Kav=0.1) that catalyzes the biosynthesis of alamethicin and shows an ATP-32PPi exchange with 6 of the 8 constituent amino acids of alamethicin. The activated amino acids are bound to the enzyme as aminoacyl adenylates and as thiolesters in a proportion of 1 : 1. About 50% of each bound amino acid could be split off with 7% TCA. The TCA-stable bound amino acid could be split by mercury acetate, hydroxylamine and performic acid. N-ethylmaleimide blocked the binding of 50% of the amino acids to the enzyme, proving that some of the amino acids first bound as aminoacyl adenylates are then transferred into a thiolester bond.
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000408:Alamethicin / Q000096:biosynthesis*; D000596:Amino Acids / Q000378:metabolism; D049148:Aminoacylation; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D002474:Cell-Free System; D004917:Erythromycin / Q000494:pharmacology; D003904:Mitosporic Fungi / Q000378:metabolism*; D011691:Puromycin / Q000494:pharmacology; D012260:Ribonucleases / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014242:Trichoderma / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D013439:Sulfhydryl Reagents; D000408:Alamethicin; D000249:Adenosine Monophosphate; D011691:Puromycin; D004917:Erythromycin; D000255:Adenosine Triphosphate; D012260:Ribonucleases