| Identification and characterization of hydrophobic microcystins in Canadian freshwater cyanobacteria. | |
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MedLine Citation:
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PMID: 8146867 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Hepatotoxic microcystins produced by cyanobacteria in freshwater lakes represent a significant health hazard to humans and agricultural livestock. Liquid chromatography (LC)-linked protein phosphatase (PPase) bioassay analysis of blooms of Microcystis aeruginosa produced in a Canadian drinking water lake identified several PPase inhibitors with significantly greater hydrophobicity than microcystin-LR, based on their retention time on C18 reverse phase LC columns. Seven PPase inhibitors were purified to homogeneity by bioassay-guided fractionation involving Sephadex LH-20 chromatography and two-step reverse phase at pH 6.5 and 2.0. One of the PPase inhibitors, isolated in a final yield of 1.5 micrograms/g lyophilized cyanobacteria, was identified as microcystin-LL by amino acid analysis and mass spectrometry. A further PPase inhibitor (20 ng/g cyanobacteria) was identified as microcystin-LL but with D-Ala replaced by an unknown amino acid. Four PPase inhibitors (< 20 ng/g cyanobacteria) were characterized by amino acid analysis and identified as microcystin-LV, -LM, -LF and -LZ (where Z represents an unknown hydrophobic amino acid). A further microcystin was also identified (< 10 ng/g cyanobacteria) in which arginine was apparently absent. The biological activity of the seven microcystins as inhibitors of the catalytic subunit of protein phosphatase-1 (PP-1c) was compared with microcystin-LR and motuporin (a hydrophobic analogue of nodularin). All of the compounds inhibited PP-1c with IC50 values of 0.06-0.4 nM, consistent with their identification as microcystins. These findings further demonstrate the applicability of a sensitive PPase bioassay for the identification of variant microcystins in the natural environment. |
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Authors:
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M Craig; T L McCready; H A Luu; M A Smillie; P Dubord; C F Holmes |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Toxicon : official journal of the International Society on Toxinology Volume: 31 ISSN: 0041-0101 ISO Abbreviation: Toxicon Publication Date: 1993 Dec |
Date Detail:
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Created Date: 1994-05-05 Completed Date: 1994-05-05 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 1307333 Medline TA: Toxicon Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 1541-9 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, University of Alberta, Edmonton, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acids
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analysis Canada Chromatography, Liquid Cyanobacteria / chemistry* Eutrophication / physiology Microcystins Peptides, Cyclic / analysis*, chemistry, pharmacology Phosphoprotein Phosphatases / analysis, antagonists & inhibitors Protein Phosphatase 1 Spectrophotometry, Ultraviolet Water Microbiology Water Supply / analysis |
| Chemical | |
Reg. No./Substance:
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0/Amino Acids; 0/Microcystins; 0/Peptides, Cyclic; 77238-39-2/microcystin; EC 3.1.3.16/Phosphoprotein Phosphatases; EC 3.1.3.16/Protein Phosphatase 1 |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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