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Champacyclin, a New Cyclic Octapeptide from Streptomyces Strain C42 Isolated from the Baltic Sea
Technical University of Berlin, Institute for Chemistry, Straße des 17. Juni 124, Berlin 10623, Germany
GEOMAR Helmholtz Center for Ocean Research Kiel, Marine Microbiology, Düsternbrooker Weg 20, Kiel 24105, Germany
These authors contributed equally to this work.
* Authors to whom correspondence should be addressed.
Received: 22 October 2013; in revised form: 14 November 2013 / Accepted: 15 November 2013 / Published: 2 December 2013
Abstract: New isolates of Streptomyces champavatii were isolated from marine sediments of the Gotland Deep (Baltic Sea), from the Urania Basin (Eastern Mediterranean), and from the Kiel Bight (Baltic Sea). The isolates produced several oligopeptidic secondary metabolites, including the new octapeptide champacyclin (1a) present in all three strains. Herein, we report on the isolation, structure elucidation and determination of the absolute stereochemistry of this isoleucine/leucine (Ile/Leu = Xle) rich cyclic octapeptide champacyclin (1a). As 2D nuclear magnetic resonance (NMR) spectroscopy could not fully resolve the structure of (1a), additional information on sequence and configuration of stereocenters were obtained by a combination of multi stage mass spectrometry (MSn) studies, amino acid analysis, partial hydrolysis and subsequent enantiomer analytics with gas chromatography positive chmical ionization/electron impact mass spectrometry (GC-PCI/EI-MS) supported by comparison to reference dipeptides. Proof of the head-to-tail cyclization of (1a) was accomplished by solid phase peptide synthesis (SPPS) compared to an alternatively side chain cyclized derivative (2). Champacyclin (1a) is likely synthesized by a non-ribosomal peptide synthetase (NRPS), because of its high content of (d)-amino acids. The compound (1a) showed antimicrobial activity against the phytopathogen Erwinia amylovora causing the fire blight disease of certain plants.
Keywords: Streptomyces champavatii; antimicrobial activity; fire blight; cyclic peptides; sequence ladder analysis; chiral GC-PCI/EI-MS; ESI-Ion-Trap-MSn; solid phase peptide synthesis (SPPS); on-resin cyclization; 2D NMR
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Pesic, A.; Baumann, H.I.; Kleinschmidt, K.; Ensle, P.; Wiese, J.; Süssmuth, R.D.; Imhoff, J.F. Champacyclin, a New Cyclic Octapeptide from Streptomyces Strain C42 Isolated from the Baltic Sea. Mar. Drugs 2013, 11, 4834-4857.
Pesic A, Baumann HI, Kleinschmidt K, Ensle P, Wiese J, Süssmuth RD, Imhoff JF. Champacyclin, a New Cyclic Octapeptide from Streptomyces Strain C42 Isolated from the Baltic Sea. Marine Drugs. 2013; 11(12):4834-4857.
Pesic, Alexander; Baumann, Heike I.; Kleinschmidt, Katrin; Ensle, Paul; Wiese, Jutta; Süssmuth, Roderich D.; Imhoff, Johannes F. 2013. "Champacyclin, a New Cyclic Octapeptide from Streptomyces Strain C42 Isolated from the Baltic Sea." Mar. Drugs 11, no. 12: 4834-4857.