title: Planktocyclin, a cyclooctapeptide protease inhibitor produced by the freshwater cyanobacterium Planktothrix rubescens.
abstract: The freshwater cyanobacterium Planktothrix rubescens produces the cyclooctapeptide cyclo(Pro-Gly-Leu-Val-Met-Phe-Gly-Val). The chemical structure is new. This homodetic cyclic octapeptide was named planktocyclin ( 1). It consists solely of proteinogenic l-amino acids and is a strong inhibitor of mammalian trypsin and alpha-chymotrypsin and a moderately active inhibitor of human recombinant caspase-8. Mass spectrometric and 2D-NMR spectroscopic data allowed the determination of its structure. Synthetic planktocyclin was identical to the natural product.
authors.affiliation: Limnological Station, Institute of Plant Biology, University of Zürich, Seestrasse 187, 8802 Kilchberg, Switzerland. heibaum@gmx.ch
authors.forename: Heike I
authors.initials: HI
authors.lastname: Baumann
authors.forename: Simone
authors.initials: S
authors.lastname: Keller
authors.forename: Falko E
authors.initials: FE
authors.lastname: Wolter
authors.forename: Graeme J
authors.initials: GJ
authors.lastname: Nicholson
authors.forename: Günther
authors.initials: G
authors.lastname: Jung
authors.forename: Roderich D
authors.initials: RD
authors.lastname: Süssmuth
authors.forename: Friedrich
authors.initials: F
authors.lastname: Jüttner
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D061945:Caspase Inhibitors; D002417:Cattle; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D000458:Cyanobacteria / Q000737:chemistry*; D005618:Fresh Water; D006801:Humans; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D061945:Caspase Inhibitors; D010456:Peptides, Cyclic; D011480:Protease Inhibitors; C524912:planktocyclin; D002918:Chymotrypsin; C117608:alpha-chymotrypsin