| The biosynthesis of branched dialkylpyrazines in myxobacteria. | |
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MedLine Citation:
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PMID: 20860022 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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The biosynthesis of the volatiles 2,5- and 2,6-diisopropylpyrazine (2 and 3, resp.) released by the myxobacteria Nannocystis exedens subsp. cinnabarina (Na c29) and Chondromyces crocatus (strains Cm c2 and Cm c5) was studied. Isotopically labeled precursors and proposed pathway intermediates were fed to agar plate cultures of the myxobacteria. Subsequently, the volatiles were collected by use of a closed loop stripping apparatus (CLSA), and incorporation into the pyrazines was followed by GC/MS analysis. [(2)H(8)]Valine was smoothly incorporated into both pyrazines clearly establishing their origin from the amino acid pool. The cyclic dipeptide valine anhydride (16)--a potential intermediate on the biosynthetic pathway to branched dialkylpyrazines--was synthesized containing (2)H(1) labels in specific positions. Feeding of [(2)H(16)]-16 and [(2)H(12)]-16 in both valine subunits mainly resulted in the formation of pyrazines derived from only one labeled amino acid, whereas only traces of the expected pyrazines with two labeled subunits were found. To investigate the origin of nitrogen in the pyrazines, a feeding experiment with [(15)N]valine was performed, resulting in the incorporation of the (15)N label. The results contradict a biosynthetic pathway via cyclic dipeptides, but rather point to a pathway on which valine is reduced to valine aldehyde. Its dimerization to 2,5-diisopropyldihydropyrazine 36 and subsequent oxidation results in 2. The proposed biosynthetic pathway neatly fits the results of earlier labeling studies and also explains the formation of the regioisomer 2,6-diisopropylpyrazine 3 by isomerization during the first condensation step of two molecules valine aldehyde. A general biosynthetic pathway to different classes of pyrazines is presented. |
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Authors:
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Thorben Nawrath; Jeroen S Dickschat; Brigitte Kunze; Stefan Schulz |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Chemistry & biodiversity Volume: 7 ISSN: 1612-1880 ISO Abbreviation: Chem. Biodivers. Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-09-22 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101197449 Medline TA: Chem Biodivers Country: Switzerland |
Other Details:
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Languages: eng Pagination: 2129-44 Citation Subset: IM |
Affiliation:
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Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, Braunschweig. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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