title: Calcaripeptides A-C, cyclodepsipeptides from a Calcarisporium strain.
abstract: The isolation and structure elucidation of the novel calcaripeptides A (1), B (2), and C (3) and studies on their biosynthetic origin are described. The calcaripeptides were identified from Calcarisporium sp. strain KF525, which was isolated from the German Wadden Sea. Compounds 1-3 are macrocyclic structures composed of a proline and a phenylalanine residue as well as a nonpeptidic substructure. Structure elucidation was achieved by applying one- and two-dimensional NMR spectroscopy supported by high-resolution mass spectrometry. X-ray crystallography was performed to determine the relative configuration of 1. The absolute configuration of 1 was assigned by HPLC of the amino acids after hydrolysis of the molecule and derivatization with chiral agents. Studies on the biosynthesis by feeding ¹³C-labeled substrates revealed that the nonpeptidic part of 1 originates from acetate and l-methionine. The involvement of a hybrid between a polyketide synthase and a nonribosomal peptide synthetase in the biosynthesis of the calcaripeptides is discussed.
authors.affiliation: Kieler Wirkstoff-Zentrum KiWiZ at the GEOMAR Helmholtz Centre for Ocean Research Kiel , Am Kiel-Kanal 44, 24106 Kiel, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Silber
authors.forename: Birgit
authors.initials: B
authors.lastname: Ohlendorf
authors.forename: Antje
authors.initials: A
authors.lastname: Labes
authors.forename: Christian
authors.initials: C
authors.lastname: Näther
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Imhoff
mesh_terms: D002851:Chromatography, High Pressure Liquid; D018360:Crystallography, X-Ray; D047630:Depsipeptides / Q000737:chemistry / Q000302:isolation & purification*; D008386:Marine Biology; D008715:Methionine / Q000378:metabolism; D003904:Mitosporic Fungi / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009792:Oceans and Seas; D010453:Peptide Synthases / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry
chemical_list: D047630:Depsipeptides; C584592:calcaripeptide A; C584594:calcaripeptide B; C584593:calcaripeptide C; D010649:Phenylalanine; D008715:Methionine; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase