title: Isolation of Microcystins from the Cyanobacterium Planktothrix rubescens Strain No80.
abstract: Three minor microcystins have been isolated from a Planktothrix rubescens strain. Their structures have been elucidated by one- and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the compounds [Asp(3),(E)-Dhb(7)]MC-LY (1), [Asp(3),(E)-Dhb(7)]MC-HtyW (2), and [Asp(3),(E)-Dhb(7)]MC-LW (3). The amino acids found at the variable positions 2 and 4 of the microcystin core structure are in accordance with the predicted amino acid substrate activation selectivities of the non-ribosomal peptide synthetases McyA and McyB described earlier for this strain. All structural microcystin variants produced by this strain were shown to inhibit protein phosphatase 1 in the nanomolar range.
authors.affiliation: Cyano Biotech GmbH, Magnusstr. 11, 12489 Berlin, Germany ; Interfaculty Institute for Microbiology and Infection Medicine Tübingen, Eberhard Karls University Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
authors.forename: Timo H J
authors.initials: TH
authors.lastname: Niedermeyer
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schmieder
authors.affiliation: Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, 5310 Mondsee, Austria.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kurmayer
keywords: Cyanobacteria; Microcystins; Planktothrix; Protein phosphatase inhibition