Some new n.m.r. methods for tracing the fate of hydrogen in biosynthesis

Garson, M. J.; Staunton, James

doi:10.1039/cs9790800539

Cited by 51 publications

(22 citation statements)

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“…(d) The retention of the carbon-oxygen bond at C-11 indicates that the tetrahydrofuran ring is formed by attack of a C-11 hydroxy function at C-8. A mechanism for this consistent with the observed 2 H and 1 8 0 labelling would be nucleophilic addition onto a quinonemethide intermediate (7) formed (Scheme 2) by oxidation of (6), the hydroxylated derivative of (5). A similar ring closure mechanism has been proposed in granaticin biosynthesis," and is supported by the co-occurrence of monocerin and fusarentin methyl ether (2) in F. larvarurn.…”

supporting

confidence: 69%

Biosynthesis of monocerin. Incorporation of 2H-, 13C-, and 18O-labelled acetates by Drechslera ravenelii

Scott¹,

Simpson²,

Trimble³

et al. 1984

J. Chem. Soc., Chem. Commun.

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Incorporation of 2H-, 13C-, and 180-labelled acetates into monocerin (1) by cultures of Drechslera ravenelii and analysis of the enriched metabolites by 2H and 13C n.m.r. spectroscopy indicate a heptaketide origin; observation of 2H and 1 8 0 isotope shifts in the 13C n.m.r. spectrum allows the fate of acetate-derived hydrogen and oxygen on incorporation into monocerin to be followed and conclusions on the mechanism of formation of the fused furobenzopyrone ring system to be drawn.

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supporting

confidence: 69%

Biosynthesis of monocerin. Incorporation of 2H-, 13C-, and 18O-labelled acetates by Drechslera ravenelii

Scott¹,

Simpson²,

Trimble³

et al. 1984

J. Chem. Soc., Chem. Commun.

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“…However, the mechanisms and sequence by which these units are linked remain largely speculative, partly because of lack of methods to follow changes in intermediate oxidation states. In response there is agrowing interest in determination of the biosynthetic fate of precursor hydrogens using 2H nmr (2) and of oxygens using mass spectrometry (3,4). The latter technique can detect both commonlyemployed stable isotopes of oxygen, I7O and IsO, but ascertaining the exact structure of the mass spectrometric fragments in partially-labeled polyoxygenated molecules is often difficult.…”

mentioning

confidence: 99%

Biosynthetic studies using ¹⁸O isotope shifts in ¹³C nuclear magnetic resonance

Vederas¹

1982

Can. J. Chem.

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JOHN C. VEDERAS. Can. J. Chem. 60, 1637 (1982). Isotopic substitution with oxygen-18 induces an observable upfield shift in the 13C nmr positions ofdirectly-attached carbons, and in some cases, P-carbons. The magnitudes of these shifts range from about 0.05 ppm to 0.01 ppm, and are dependent on structure in an empirically predictable fashion. Incorporation of doubly labeled (I3C, 180) precursors into polyketides followed by I3C nmr analysis can identify carbon-oxygen bonds remaining intact during microbial biosynthesis. This technique has been applied to studies on antibiotics such as brefeldin A, cytochalasin B, granaticin, and lasalocid A, as well as aflatoxin precursors such as averufin, versicolorin A, and sterigmatocystin. JOHN C. VEDERAS. Can. J. Chem. 60, 1637 (1982). La substitution isotopique par de I'oxygkne-18 induit, en rmn du "C, un dkplacement chimique observable vers les hauts champs des positions des atomes de carbone qui leur sont directement liCs et, dans certains cas, des dkplacements des atomes de carbone en position p. L'ordre de grandeur de ces dkplacements varie de 0,OSppm 2 0.01 ppm et ils dkpendent d'une f a~o n empirique de la structure. L'incorporation de prkcurseurs doublement marquks (13C, 180) dans les polycktides suivie d'une analyse par rmn du I3C permet d'identifier les liaisons carbone-oxygene qui demeurent intactes durant la synthkse microbienne. On a utilise cette technique pour ktudier les antibiotiques tels la brefeldine A, la cytochalasine B, la granaticine et la lasalocide A de m&me que des prkcurseurs d'aflatoxine tels que I'avkrufine, la versicolorine A et la stkrigmatocystine.[Traduit par le journal]During the last decade the development of I3C nmr techniques in biosynthesis has elucidated the arrangement of precursor units in carbon skeletons of most classes of secondary metabolites (1). However, the mechanisms and sequence by which these units are linked remain largely speculative, partly because of lack of methods to follow changes in intermediate oxidation states. In response there is agrowing interest in determination of the biosynthetic fate of precursor hydrogens using 2H nmr (2) and of oxygens using mass spectrometry (3,4). The latter technique can detect both commonlyemployed stable isotopes of oxygen, I7O and IsO, but ascertaining the exact structure of the mass spectrometric fragments in partially-labeled polyoxygenated molecules is often difficult. Frequently preliminary specific labeling experiments or chemical degradations are necessary (4). Unlike 160 and IsO, oxygen-17 has a nuclear spin (512) and can be observed directly by nmr. Unfortunately its use in biological studies (5, 6) has been limited by low natural abundance (0.037%) and consequent expense, as well as by broadness of nmr signals due to its quadrupole and spin-spin coupling. Recently, investigations by Boyer and coworkers (7), Risley and Van Etten (8), Darensbourg et 01. (9), and our group (10) have confirmed the theoretical prediction (1 1) that the more abundant oxygen-18 (0.204%) can be in...

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“…spectrum in which many of the peaks appear doubled. Therefore the natural product was treated with sodium borohydride, followed by methylation of the resulting acid with diazomethane to give the derivative (2) in which one of the chiral centres has been destroyed (Scheme 1). The 13C n.m.r.…”

mentioning

confidence: 99%

A 2H and 13C n.m.r. study of the biosynthesis of the polyketide isocoumarin residue of canescin in Aspergillus malignus from [1,2-13C2]-, and [1-13C, 2-2H3]acetates, [Me-13C, 2H3]methionine, 6,8-dihydroxy-3,7-dimethylisocoumarin, and 6,8-dihydroxy-7-formyl-3-methylisocoumarin

Lewis¹,

Staunton²,

Sunter³

1986

J. Chem. Soc., Chem. Commun.

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Some new n.m.r. methods for tracing the fate of hydrogen in biosynthesis

Cited by 51 publications

References 0 publications

Biosynthesis of monocerin. Incorporation of 2H-, 13C-, and 18O-labelled acetates by Drechslera ravenelii

Biosynthesis of monocerin. Incorporation of 2H-, 13C-, and 18O-labelled acetates by Drechslera ravenelii

Biosynthetic studies using ¹⁸O isotope shifts in ¹³C nuclear magnetic resonance

A 2H and 13C n.m.r. study of the biosynthesis of the polyketide isocoumarin residue of canescin in Aspergillus malignus from [1,2-13C2]-, and [1-13C, 2-2H3]acetates, [Me-13C, 2H3]methionine, 6,8-dihydroxy-3,7-dimethylisocoumarin, and 6,8-dihydroxy-7-formyl-3-methylisocoumarin

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Some new n.m.r. methods for tracing the fate of hydrogen in biosynthesis

Cited by 51 publications

References 0 publications

Biosynthesis of monocerin. Incorporation of 2H-, 13C-, and 18O-labelled acetates by Drechslera ravenelii

Biosynthesis of monocerin. Incorporation of 2H-, 13C-, and 18O-labelled acetates by Drechslera ravenelii

Biosynthetic studies using 18O isotope shifts in 13C nuclear magnetic resonance

A 2H and 13C n.m.r. study of the biosynthesis of the polyketide isocoumarin residue of canescin in Aspergillus malignus from [1,2-13C2]-, and [1-13C, 2-2H3]acetates, [Me-13C, 2H3]methionine, 6,8-dihydroxy-3,7-dimethylisocoumarin, and 6,8-dihydroxy-7-formyl-3-methylisocoumarin

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Biosynthetic studies using ¹⁸O isotope shifts in ¹³C nuclear magnetic resonance