Antibiotics: Actinomycin D - structure model

- University of Hamburg - Faculty of Biology - Biocenter Klein Flottbek

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The antibiotic actinomycin D (produced by Streptomyces antibioticus) binds to DNA duplexes, thereby interfering with the action of enzymes engaged in replication and transcription. The molecule consists of a phenoxazone ring system

, to which two cyclic pentapeptides are attached

. The peptides are synthesized nonribosomally and contain also non-protein amino acids

. They are formed by a threonine

(connecting to the phenoxazone), a D-alanine

, a proline

, a sarcosine

and a methyl-valine

. An ester bond to the threonine closes the ring to a lactone

. The aromatic ring system

is well apt to intercalate into DNA, preferably at GC steps.

For structural investigations selfcomplementary stretches of DNA containing central GC basepairs were synthesized.

Click here for structural details on intercalation in these DNA sequences:
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