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Updated: Sep 9, 2026

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 16, 2013
Studies on the pyrrolizidine antitumor agent, clazamycin: interconversion of clazamycins A and B
1Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin 78712.
Abstract:
Clazamycin, a novel pyrrolizidine antitumor antibiotic, exists in aqueous solution as a mixture of two epimers, clazamycins A and B [1A, 1B], the ratio of which is pH dependent. Several lines of evidence are presented, including the results of trapping experiments and a study demonstrating base promoted interconversion of the two forms, that implicate an azacyclooctenone species [3] as an intermediate in the interconversion process. This result supports a previous observation, that the C6a carbinolamidine hydroxyl of clazamycin is unreactive towards nucleophiles and may be significant in helping to elucidate the mechanism of action of this antibiotic.
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