Abstract
Two new protein phosphatase inhibitors, oscillamide B (1) and C (2), were isolated from the cyanobacteria Planktothrix (Oscillatoria) agardhii and P. rubescens. The structures of the inhibitors were elucidated by analysis of HRFABMS, 1D and 2D NMR spectra, and chemical degradation. These inhibitors are ureido-containing cyclic peptides and inhibited serine/threonine protein phosphatases PP1 and PP2A. The inhibitory activities were closely related to the Arg and N-Me-Hty residues in the peptides.
MeSH terms
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Chromatography, High Pressure Liquid
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Cyanobacteria / chemistry*
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Enzyme Inhibitors / chemistry
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Enzyme Inhibitors / isolation & purification*
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Magnetic Resonance Spectroscopy
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Mass Spectrometry
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Molecular Structure
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Peptides, Cyclic / chemistry
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Peptides, Cyclic / isolation & purification*
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Phosphoprotein Phosphatases / antagonists & inhibitors*
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Phosphoprotein Phosphatases / metabolism
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Phosphorylation
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Substrate Specificity
Substances
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Enzyme Inhibitors
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Peptides, Cyclic
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anabaenopeptin F
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oscillamide B
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oscillamide C
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oscillamide Y
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Phosphoprotein Phosphatases