Ein Dioxobilan als Produkt eines divergenten Chlorophyllabbaus in Spitzahorn

Müller, Thomas; Rafelsberger, Martina; Vergeiner, Clemens; Kräutler, Bernhard

doi:10.1002/ange.201103934

Cited by 14 publications

(7 citation statements)

References 35 publications

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“…The major nonfluorescent DCC fractions with retention times ( t R ) of 38.1, 43.6, 45.7 and 46.8 min had UV spectra (Figure S2 in the Supporting Information) similar to those of structurally characterized DNCCs. [ 5 , 15 – 17 ] Their CD spectra were also similar to each other (see the Supporting Information) and had the same characteristics as those of several DCCs from senescent leaves of wild-type Arabidopsis. [ 18 ] The molecular formula (C 34 H 40 N 4 O 8 ) of the polar catabolite at t R =38.1 min and designated here as At-mes16 -DNCC-38 ( 3 ), was derived from its ESI mass spectrum ([ M +H] + ion at m / z 633.1).…”

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confidence: 79%

“…A double doublet (dd) at δ =4.09 ppm and a triplet at δ =4.35 ppm indicated H atoms at the positions C-1 and C-9, typical for DNCCs. [ 15 , 16 ] Analysis of 2D NMR spectra (Figure S3 in the Supporting Information) revealed the constitution of At - mes16 -DNCC-38 ( 3 ). It is a new natural DNCC (Figure 4 ).…”

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confidence: 99%

“…The existence of these DNCCs suggests the intermediacy of corresponding DFCCs, from which DNCCs may arise by a stereoselective isomerization. [ 8 , 15 , 18 ] Presumably, the corresponding, but elusive, DFCCs are the result of an oxidative (CYP89A9 induced) deformylation of p FCC, followed (in the case of 3 ) by enzyme-catalyzed hydroxylation at C-8 2 . Interestingly, the in vitro experiment with p FCC and CYP89A9 furnished two C-9 epimeric DFCCs,[ 18 ] suggesting a stereo-unselective protonation outside of this enzyme.…”

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confidence: 99%

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Hydroxymethylated Phyllobilins: A Puzzling New Feature of the Dioxobilin Branch of Chlorophyll Breakdown

Süssenbacher

Christ

Hörtensteiner

et al. 2013

Chemistry A European J

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Colorless nonfluorescent chlorophyll (Chl) catabolites (NCCs) are formyloxobilin-type phyllobilins, which are considered the typical products of Chl breakdown in senescent leaves. However, in degreened leaves of some plants, dioxobilin-type Chl catabolites (DCCs) predominate, which lack the formyl group of the NCCs, and which arise from Chl catabolites by oxidative removal of the formyl group by a P450 enzyme. Here a structural investigation of the DCCs in the methylesterase16 mutant of Arabidopsis thaliana is reported. Eight new DCCs were identified and characterized structurally. Strikingly, three of these DCCs carry stereospecifically added hydroxymethyl groups, and represent bilin-type linear tetrapyrroles with an unprecedented modification. Indeed, DCCs show a remarkable structural parallel, otherwise, to the bilins from heme breakdown.

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confidence: 99%

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Hydroxymethylated Phyllobilins: A Puzzling New Feature of the Dioxobilin Branch of Chlorophyll Breakdown

Süssenbacher

Christ

Hörtensteiner

et al. 2013

Chemistry A European J

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“…The here described oxidative path involving NCCs may open a natural route to further breakdown via the colored Chl catabites, and to eventual degradation, altogether, of tetrapyrrolic phyllobilins. Similar oxidative transformations of DNCCs, the dioxobilin analogues of NCCs,[ 6 , 18 ] may provide DYCCs and their further descendants. Recent studies in our labs have, indeed, provided evidence for the occurrence of DYCCs in extracts of yellow senescent grapevine leaves.…”

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confidence: 99%

“…[ 4 ] In senescent leaves of a variety of higher plants, the rapidly formed colorless NCCs[ 5 ] were typically observed as the “final” products of Chl breakdown. In other leaves, mostly colorless “dioxobilin-type” NCCs (DNCCs) were found,[ 6 ] formal (but not genuine) deformylation products of NCCs. [ 6b ] The typical accumulation of colorless and photo-inactive phyllobilins was interpreted as the result of a controlled Chl detoxification process (see Scheme 1 ).…”

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confidence: 99%

Stereo‐ and Regioselective Phyllobilane Oxidation in Leaf Homogenates of the Peace Lily (Spathiphyllum wallisii): Hypothetical Endogenous Path to Yellow Chlorophyll Catabolites

Vergeiner

Ulrich

et al. 2014

Chemistry A European J

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In senescent leaves, chlorophyll typically is broken down to colorless and essentially photo-inactive phyllobilanes, which are linear tetrapyrroles classified as “nonfluorescent” chlorophyll catabolites (NCCs) and dioxobilane-type NCCs (DNCCs). In homogenates of senescent leaves of the tropical evergreen Spathiphyllum wallisii, when left at room temperature and extracted with methanol, the major endogenous, naturally formed NCC was regio- and stereoselectively oxidized (in part) to a mixture of its 15-hydroxy and 15-methoxy derivative. In the absence of methanol in the extract, only the 15-OH-NCC was observed. The endogenous oxidation process depended upon molecular oxygen. It was inhibited by carbon monoxide, as well as by keeping the leaf homogenate and extract at low temperatures. The remarkable “oxidative activity” was inactivated by heating the homogenate for 10 min at 70 °C. Upon addition of a natural epimeric NCC (epiNCC) to the homogenate of senescent or green Sp. wallisii leaves at room temperature, the exogenous epiNCC was oxidized regio- and stereoselectively to 15-OH-epiNCC and 15-OMe-epiNCC. The identical two oxidized epiNCCs were also obtained as products of the oxidation of epiNCC with dicyanodichlorobenzoquinone (DDQ). Water elimination from 15-OH-epiNCC occurred readily and gave a known “yellow” chlorophyll catabolite (YCC). The endogenous oxidation process, described here, may represent the elusive natural path from the colorless NCCs to yellow and pink coloured phyllobilins, which were found in (extracts of) some senescent leaves.

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Ein fluoreszierender Chlorophyll‐Katabolit des Dioxobilin‐Typs als transientes und frühes Zwischenprodukt des Dioxobilin‐Astes des Chlorophyllabbaus in Arabidopsis thaliana

2015

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Der Chlorophyllabbau findet in hçheren Pflanzen über den "PaO/Phyllobilin"-Weg statt. Dabei werden zwei wichtige Phyllobilin-Typen gebildet, die charakteristischen 1-Formyl-19-oxobiline und die vor kurzem entdeckten 1,19-Dioxobiline.D ie hypothetische Verzweigung ist immer noch unbekannt, an welcher sich die ursprünglich gebildeten [2] was den Wegf ür die weitere strukturgeleitete Erforschung des "PaO/Phyllobilin"-Abbaus des Chlorophylls ebnete.[3] Eine oxidative Spaltung des Chl-Makroringes führt demnach zu 1-Formyl-19-oxobilinen und çffnet damit den Wegzuden verschiedenen bilinartigen Kataboliten des Chls, den Phyllobilinen. [3b,d] Vorkurzem wurde außerdem entdeckt, dass sich der Chl-Abbau "verzweigt" und sich Chl-Kataboliten vom 1,19-Dioxobilin-Typ (DCCs) in einer zweiten Hauptfamilie der Phyllobiline entstehen.[Phyllobiline,z ud enen etwa die nichtfluoreszierenden ChlKataboliten vom 1,19-Dioxobilin-Typ (DNCCs) gehçren, sind überwiegend farblos.[5] Ursprünglich wurde davon ausgegangen, dass DNCCs die Deformylierungsprodukte der "nichtfluoreszierenden" Chl-Kataboliten (NCCs) darstellen, [5a] aber bisher konnte der natürliche Schritt, der 1-Formyl-19-oxobiline in DCCs umwandelt, noch nicht geklärt werden.[3d] Die rätselhafte stereochemische Vielfalt der natürlichen DNCCs ließ NCCs nicht als wahrscheinliche Vorstufen der DNCCs erscheinen.[5b] Ausd iesem Grund wurde eine frühere Abzweigung im "PaO/Phyllobilin"-Abbauweg von Chl vermutet, in der ein noch unbekannter fluoreszierender Chl-Katabolit des Dioxobilin-Typs (DFCC) die Vorstufe der DNCCs wäre (Abbildung 1).[5b]Ein außergewçhnliches Cytochrom-P450-Enzym (CYP89A9) wurde vor kurzem in Arabidopsis thaliana (A. thaliana)i dentifiziert, das die In-vitro-Deformylierung eines "primären" fluoreszierenden Chl-Kataboliten (pFCC) zu epimeren "primären" DFCCs (pDFCCs) katalysierte.[6] In einer schwach sauren Lçsung isomerisierten die epimeren pDFCCs schnell weiter zu einem entsprechenden Paar DNCCs.Die beiden Schlüsselschritte im "Dioxobilin-Zweig" des Chl-Abbaus schienen also geklärt zu sein.[6] Leider ließen diese Befunde weder einen Rückschluss auf das stereochemische Ergebnis der hypothetischen DFCC-DNCC Isomerisierung zu,[5b] noch wurde dadurch ein wesentlicher Schritt im "natürlichen" Dioxobilin-Weg durch die In-vitro-Enzymreaktion identifiziert. Wirw aren nun jedoch in der Lage, einen transient existierenden, natürlichen DFCC in einem frühen Seneszenz-Stadium von Blättern der Modellpflanze A. thaliana abzufangen und dessen Isomerisierung zu einem DNCC zu beobachten. Diese Isomerisierung war schnell und führte äußerst stereoselektiv zum At-DNCC-33, dem wichtigsten natürlichen DNCC in den seneszenten A.-thalianaBlättern (dieser DNCC wurde früher als At-NDCC-1 bezeichnet). [6] Um dieses frühe Zwischenprodukt des Chl-Abbaus im A.-thaliana-Wildtypus abzufangen, wurden frische Extrakte von 2T age dunkel-inkubierten Blättern (frühes Seneszenz-Stadium) analysiert. Die HPLC-Analyse zeigte,m it früheren Untersuchungen übereinstimmend, eine Vielfalt an Chl-Ka...

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Ein Dioxobilan als Produkt eines divergenten Chlorophyllabbaus in Spitzahorn

Cited by 14 publications

References 35 publications

Hydroxymethylated Phyllobilins: A Puzzling New Feature of the Dioxobilin Branch of Chlorophyll Breakdown

Hydroxymethylated Phyllobilins: A Puzzling New Feature of the Dioxobilin Branch of Chlorophyll Breakdown

Stereo‐ and Regioselective Phyllobilane Oxidation in Leaf Homogenates of the Peace Lily (Spathiphyllum wallisii): Hypothetical Endogenous Path to Yellow Chlorophyll Catabolites

Ein fluoreszierender Chlorophyll‐Katabolit des Dioxobilin‐Typs als transientes und frühes Zwischenprodukt des Dioxobilin‐Astes des Chlorophyllabbaus in Arabidopsis thaliana

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