Substrate free radicals are intermediates in ligninase catalysis.
Identifieur interne : 001030 ( Main/Exploration ); précédent : 001029; suivant : 001031Substrate free radicals are intermediates in ligninase catalysis.
Auteurs : K E Hammel ; B. Kalyanaraman ; T K KirkSource :
- Proceedings of the National Academy of Sciences of the United States of America [ 0027-8424 ] ; 1986.
Descripteurs français
- KwdFr :
- Basidiomycota (enzymologie), Catalyse (MeSH), Chromatographie en phase liquide à haute performance (MeSH), Chromatographie gazeuse-spectrométrie de masse (MeSH), Dérivés du benzène (métabolisme), Oxygénases (métabolisme), Radicaux libres (MeSH), Spectroscopie de résonance de spin électronique (MeSH).
- MESH :
English descriptors
- KwdEn :
- MESH :
- chemical , metabolism : Benzene Derivatives, Oxygenases.
- enzymology : Basidiomycota.
- Catalysis, Chromatography, High Pressure Liquid, Electron Spin Resonance Spectroscopy, Free Radicals, Gas Chromatography-Mass Spectrometry.
Abstract
The H2O2-requiring ligninase of the basidiomycete Phanerochaete chrysosporium oxidatively cleaves both lignin and lignin model compounds between C alpha and C beta (C-1 and C-2) of their aliphatic side chains. Previous work has demonstrated a reaction mechanism by which ligninase oxidizes aromatic substrates to their cation radicals, which then undergo side chain cleavage to yield carbon-centered free radicals. These carbon-centered radicals add O2 to give substrate peroxyl radicals that react further to yield the hydroxylated and carbonylated end products usually seen in experiments with ligninase. To investigate this radical mechanism, we have now designed three dimeric lignin models: 1-(3,4-dimethoxyphenyl)-2-phenylethanol (I), 1-(3,4-dimethoxyphenyl)-2-phenylpropanol (II), and 1-(3,4-dimethoxyphenyl)-2-methyl-2-phenylpropanol (III). The following results were obtained when these models were oxidized by ligninase: methyl groups at C beta of the substrate favored C alpha-C beta cleavage versus C alpha oxidation to the ketone. GC/MS and HPLC analysis showed that II gave a radical coupling dimer, 2,3-diphenylbutane, as a major (26% yield) reaction product under anaerobic conditions. The anaerobic oxidation of III yielded 2,3-dimethyl-2,3-diphenylbutane. Spin-trapping experiments with nitrosobenzene showed that model II oxidation produced alpha-methylbenzyl radicals, whereas model III oxidation gave alpha, alpha-dimethylbenzyl radicals. TLC and iodometric determinations showed that III gave cumene hydroperoxide as a major (21% yield) reaction product in air. These findings demonstrate that carbon-centered and peroxyl radicals at C beta are major products of C alpha-C beta cleavage by ligninase.
DOI: 10.1073/pnas.83.11.3708
PubMed: 3012530
PubMed Central: PMC323592
Affiliations:
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Kalyanaraman</name></author><author><name sortKey="Kirk, T K" sort="Kirk, T K" uniqKey="Kirk T" first="T K" last="Kirk">T K Kirk</name></author></titleStmt><publicationStmt><idno type="wicri:source">PubMed</idno><date when="1986">1986</date><idno type="RBID">pubmed:3012530</idno><idno type="pmid">3012530</idno><idno type="pmc">PMC323592</idno><idno type="doi">10.1073/pnas.83.11.3708</idno><idno type="wicri:Area/Main/Corpus">001036</idno><idno type="wicri:explorRef" wicri:stream="Main" wicri:step="Corpus" wicri:corpus="PubMed">001036</idno><idno type="wicri:Area/Main/Curation">001036</idno><idno type="wicri:explorRef" wicri:stream="Main" wicri:step="Curation">001036</idno><idno type="wicri:Area/Main/Exploration">001036</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en">Substrate free radicals are intermediates in ligninase catalysis.</title><author><name sortKey="Hammel, K E" sort="Hammel, K E" uniqKey="Hammel K" first="K E" last="Hammel">K E Hammel</name></author><author><name sortKey="Kalyanaraman, B" sort="Kalyanaraman, B" uniqKey="Kalyanaraman B" first="B" last="Kalyanaraman">B. Kalyanaraman</name></author><author><name sortKey="Kirk, T K" sort="Kirk, T K" uniqKey="Kirk T" first="T K" last="Kirk">T K Kirk</name></author></analytic><series><title level="j">Proceedings of the National Academy of Sciences of the United States of America</title><idno type="ISSN">0027-8424</idno><imprint><date when="1986" type="published">1986</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>Basidiomycota (enzymology)</term><term>Benzene Derivatives (metabolism)</term><term>Catalysis (MeSH)</term><term>Chromatography, High Pressure Liquid (MeSH)</term><term>Electron Spin Resonance Spectroscopy (MeSH)</term><term>Free Radicals (MeSH)</term><term>Gas Chromatography-Mass Spectrometry (MeSH)</term><term>Oxygenases (metabolism)</term></keywords><keywords scheme="KwdFr" xml:lang="fr"><term>Basidiomycota (enzymologie)</term><term>Catalyse (MeSH)</term><term>Chromatographie en phase liquide à haute performance (MeSH)</term><term>Chromatographie gazeuse-spectrométrie de masse (MeSH)</term><term>Dérivés du benzène (métabolisme)</term><term>Oxygénases (métabolisme)</term><term>Radicaux libres (MeSH)</term><term>Spectroscopie de résonance de spin électronique (MeSH)</term></keywords><keywords scheme="MESH" type="chemical" qualifier="metabolism" xml:lang="en"><term>Benzene Derivatives</term><term>Oxygenases</term></keywords><keywords scheme="MESH" qualifier="enzymologie" xml:lang="fr"><term>Basidiomycota</term></keywords><keywords scheme="MESH" qualifier="enzymology" xml:lang="en"><term>Basidiomycota</term></keywords><keywords scheme="MESH" qualifier="métabolisme" xml:lang="fr"><term>Dérivés du benzène</term><term>Oxygénases</term></keywords><keywords scheme="MESH" xml:lang="en"><term>Catalysis</term><term>Chromatography, High Pressure Liquid</term><term>Electron Spin Resonance Spectroscopy</term><term>Free Radicals</term><term>Gas Chromatography-Mass Spectrometry</term></keywords><keywords scheme="MESH" xml:lang="fr"><term>Catalyse</term><term>Chromatographie en phase liquide à haute performance</term><term>Chromatographie gazeuse-spectrométrie de masse</term><term>Radicaux libres</term><term>Spectroscopie de résonance de spin électronique</term></keywords></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">The H2O2-requiring ligninase of the basidiomycete Phanerochaete chrysosporium oxidatively cleaves both lignin and lignin model compounds between C alpha and C beta (C-1 and C-2) of their aliphatic side chains. Previous work has demonstrated a reaction mechanism by which ligninase oxidizes aromatic substrates to their cation radicals, which then undergo side chain cleavage to yield carbon-centered free radicals. These carbon-centered radicals add O2 to give substrate peroxyl radicals that react further to yield the hydroxylated and carbonylated end products usually seen in experiments with ligninase. To investigate this radical mechanism, we have now designed three dimeric lignin models: 1-(3,4-dimethoxyphenyl)-2-phenylethanol (I), 1-(3,4-dimethoxyphenyl)-2-phenylpropanol (II), and 1-(3,4-dimethoxyphenyl)-2-methyl-2-phenylpropanol (III). The following results were obtained when these models were oxidized by ligninase: methyl groups at C beta of the substrate favored C alpha-C beta cleavage versus C alpha oxidation to the ketone. GC/MS and HPLC analysis showed that II gave a radical coupling dimer, 2,3-diphenylbutane, as a major (26% yield) reaction product under anaerobic conditions. The anaerobic oxidation of III yielded 2,3-dimethyl-2,3-diphenylbutane. Spin-trapping experiments with nitrosobenzene showed that model II oxidation produced alpha-methylbenzyl radicals, whereas model III oxidation gave alpha, alpha-dimethylbenzyl radicals. TLC and iodometric determinations showed that III gave cumene hydroperoxide as a major (21% yield) reaction product in air. These findings demonstrate that carbon-centered and peroxyl radicals at C beta are major products of C alpha-C beta cleavage by ligninase.</div></front></TEI><pubmed><MedlineCitation Status="MEDLINE" Owner="NLM"><PMID Version="1">3012530</PMID><DateCompleted><Year>1986</Year><Month>07</Month><Day>09</Day></DateCompleted><DateRevised><Year>2019</Year><Month>05</Month><Day>01</Day></DateRevised><Article PubModel="Print"><Journal><ISSN IssnType="Print">0027-8424</ISSN><JournalIssue CitedMedium="Print"><Volume>83</Volume><Issue>11</Issue><PubDate><Year>1986</Year><Month>Jun</Month></PubDate></JournalIssue><Title>Proceedings of the National Academy of Sciences of the United States of America</Title><ISOAbbreviation>Proc Natl Acad Sci U S A</ISOAbbreviation></Journal><ArticleTitle>Substrate free radicals are intermediates in ligninase catalysis.</ArticleTitle><Pagination><MedlinePgn>3708-12</MedlinePgn></Pagination><Abstract><AbstractText>The H2O2-requiring ligninase of the basidiomycete Phanerochaete chrysosporium oxidatively cleaves both lignin and lignin model compounds between C alpha and C beta (C-1 and C-2) of their aliphatic side chains. Previous work has demonstrated a reaction mechanism by which ligninase oxidizes aromatic substrates to their cation radicals, which then undergo side chain cleavage to yield carbon-centered free radicals. These carbon-centered radicals add O2 to give substrate peroxyl radicals that react further to yield the hydroxylated and carbonylated end products usually seen in experiments with ligninase. To investigate this radical mechanism, we have now designed three dimeric lignin models: 1-(3,4-dimethoxyphenyl)-2-phenylethanol (I), 1-(3,4-dimethoxyphenyl)-2-phenylpropanol (II), and 1-(3,4-dimethoxyphenyl)-2-methyl-2-phenylpropanol (III). The following results were obtained when these models were oxidized by ligninase: methyl groups at C beta of the substrate favored C alpha-C beta cleavage versus C alpha oxidation to the ketone. GC/MS and HPLC analysis showed that II gave a radical coupling dimer, 2,3-diphenylbutane, as a major (26% yield) reaction product under anaerobic conditions. The anaerobic oxidation of III yielded 2,3-dimethyl-2,3-diphenylbutane. Spin-trapping experiments with nitrosobenzene showed that model II oxidation produced alpha-methylbenzyl radicals, whereas model III oxidation gave alpha, alpha-dimethylbenzyl radicals. TLC and iodometric determinations showed that III gave cumene hydroperoxide as a major (21% yield) reaction product in air. These findings demonstrate that carbon-centered and peroxyl radicals at C beta are major products of C alpha-C beta cleavage by ligninase.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Hammel</LastName><ForeName>K E</ForeName><Initials>KE</Initials></Author><Author ValidYN="Y"><LastName>Kalyanaraman</LastName><ForeName>B</ForeName><Initials>B</Initials></Author><Author ValidYN="Y"><LastName>Kirk</LastName><ForeName>T K</ForeName><Initials>TK</Initials></Author></AuthorList><Language>eng</Language><GrantList CompleteYN="Y"><Grant><GrantID>GM-29035</GrantID><Acronym>GM</Acronym><Agency>NIGMS NIH HHS</Agency><Country>United States</Country></Grant><Grant><GrantID>RR-01008</GrantID><Acronym>RR</Acronym><Agency>NCRR NIH HHS</Agency><Country>United States</Country></Grant></GrantList><PublicationTypeList><PublicationType UI="D016428">Journal Article</PublicationType><PublicationType UI="D013486">Research Support, U.S. Gov't, 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hydroperoxide</NameOfSubstance></Chemical></ChemicalList><CitationSubset>IM</CitationSubset><MeshHeadingList><MeshHeading><DescriptorName UI="D001487" MajorTopicYN="N">Basidiomycota</DescriptorName><QualifierName UI="Q000201" MajorTopicYN="N">enzymology</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D001555" MajorTopicYN="N">Benzene Derivatives</DescriptorName><QualifierName UI="Q000378" MajorTopicYN="N">metabolism</QualifierName></MeshHeading><MeshHeading><DescriptorName UI="D002384" MajorTopicYN="N">Catalysis</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D002851" MajorTopicYN="N">Chromatography, High Pressure Liquid</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D004578" MajorTopicYN="N">Electron Spin Resonance Spectroscopy</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D005609" MajorTopicYN="N">Free Radicals</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D008401" MajorTopicYN="N">Gas Chromatography-Mass Spectrometry</DescriptorName></MeshHeading><MeshHeading><DescriptorName UI="D010105" MajorTopicYN="N">Oxygenases</DescriptorName><QualifierName UI="Q000378" MajorTopicYN="Y">metabolism</QualifierName></MeshHeading></MeshHeadingList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="pubmed"><Year>1986</Year><Month>6</Month><Day>1</Day></PubMedPubDate><PubMedPubDate PubStatus="medline"><Year>1986</Year><Month>6</Month><Day>1</Day><Hour>0</Hour><Minute>1</Minute></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>1986</Year><Month>6</Month><Day>1</Day><Hour>0</Hour><Minute>0</Minute></PubMedPubDate></History><PublicationStatus>ppublish</PublicationStatus><ArticleIdList><ArticleId IdType="pubmed">3012530</ArticleId><ArticleId IdType="pmc">PMC323592</ArticleId><ArticleId IdType="doi">10.1073/pnas.83.11.3708</ArticleId></ArticleIdList><ReferenceList><Reference><Citation>Biochem Biophys Res Commun. 1983 Aug 12;114(3):1077-83</Citation><ArticleIdList><ArticleId 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