Synthesis of the antibacterial peptide cecropin A(1-33)
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 fo...
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Veröffentlicht in: | Biochemistry (Easton) 1982-09, Vol.21 (20), p.5020-5031 |
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Sprache: | eng |
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Zusammenfassung: | 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. |
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ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi00263a028 |