page_title: Cyclothiazomycin
section_title: Structure
hierarchical_section_title: Cyclothiazomycin / Structure
caption_attribution_description: English: Structure of cyclothiazomycin family of compounds
context_page_description: The cyclothiazomycins are a group of natural products, classified as thiopeptides, which are produced by various Streptomyces species of bacteria.
  These compounds are ribosomally synthesized and post-translationally modified peptides and can be further classified as thiopeptides. The overall structure of the cyclothiazomycins comprises a macrocyclic bicyclic peptide containing several thiazoles and thiazolines. The cyclothiazomycins are reported to have multiple inhibitory effects ranging from decreasing blood pressure to interfering with RNA transcription; they also exhibit some antibiotic activity.
context_section_description: The cyclothiazomycins are thiazole-containing bicyclic and macrocyclic peptides that are structurally similar to thiostrepton and noshiheptide.  Formally classified as thiopeptides within the larger family of ribosomally synthesized and post-translationally modified peptides (RiPPs), the cyclothiazomycins are initially biosynthesized as peptides which subsequently undergo chemical modifications, including macrocyclization, aromatization, cyclodehydration, and dehydrogenation. Cyclothiazomycins exist as three analogues that differ at two amino acid residues in the core peptide. The image below denotes in red the differences between the analogues as well as the amino acid sequence that becomes the final compounds.
  The structure of cyclothiazomycin A was established primarily by two-dimensional nuclear magnetic resonance spectroscopy. Cyclothiazomycin A contains a dehydroalanine and two dehydrohomoalanine residues within a bicyclic, macrocyclic scaffold composed of thiazolines, thiazoles, and a trisubstituted pyridine.
  Cyclothiazomycin B and C vary from cyclothiazomycin A at the second and third threonine residues in the core sequence of the precursor peptide. In cyclothiazomycin B, the second threonine is an arginine.  Cyclothiazomycin B exists as a pair of  diastereomers, cyclothiazomycin B1 and cyclothiazomycin B2, that differ at the configuration of one of its dehydrohomoalanine moieties. Cyclothiazomycin B1 and B2 interconvert by isomerization in solution but are stable in the solid state.
  Cyclothiazomycin C has a lysine in place of the second threonine residue found in cyclothiazomycin A and a serine residue in place of the third threonine residue, resulting in a dehydroalanine instead of the dehydrohomoalanine observed in cyclothiazomycin A.
caption: The cyclothiazomycin family of antibiotics includes cyclothiazomycins A, B, and C. The structural differences between the analogues are shown in red. Also depicted are the sequences of the peptides that are chemically modified to become the final molecules.
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