title: Synthesis of the antibacterial peptide cecropin A (1-33).
abstract: Cecropin A(1-33) was synthesized by an improved stepwise solid-phase method. The synthesis was designed to give high coupling yields and minimal amounts of byproducts. All coupling steps were monitored for completion by a new ninhydrin procedure, and the fully protected peptide-resin was analyzed for deletion peptides by the solid-phase Edman preview technique. Both methods indicated that the average coupling yield was greater than 99.8%. The unpurified peptide mixture resulting from HF cleavage and extraction into 10% acetic acid was analyzed by reverse-phase high-pressure liquid chromatography, and 93% of the total product was shown to be the desired [Trp(For)2]cecropin A(1-33), indicating an average yield per synthetic cycle of 99.8%. Removal of the formyl group at pH 9, followed by ion-exchange chromatography, gave the purified product. Cecropin A(1-33) showed antibacterial activity against both Gram-positive and Gram-negative bacteria. Against Escherichia coli, the activity was only slightly lower than that of the natural 37-residue cecropin A when tested over a 100-fold concentration range; the minimum inhibitory concentration was approximately 1 microM. The formyl derivative was somewhat less effective in killing E. coli than the free 1-33 peptide. The antibacterial activity was discussed in terms of an amphipathic alpha-helix structure and the binding of the peptide to bacterial membranes.
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis*; D000893:Anti-Inflammatory Agents / Q000138:chemical synthesis*; D001410:Bacillus megaterium / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects; D055598:Chemical Phenomena; D002621:Chemistry; D004926:Escherichia coli / Q000187:drug effects; D007301:Insect Hormones / Q000138:chemical synthesis*; D019476:Insect Proteins; D008956:Models, Chemical; D010446:Peptide Fragments; D010455:Peptides / Q000138:chemical synthesis; D011550:Pseudomonas aeruginosa / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D007301:Insect Hormones; D019476:Insect Proteins; D010446:Peptide Fragments; D010455:Peptides; C036095:cecropin A (1-33)