Natural Deuterium Distribution in Fatty Acids Isolated from Peanut Seed Oil: A Site-Specific Study by Quantitative 2H NMR Spectroscopy

Duan, Jia-Rong; Billault, Isabelle; Mabon, Françoise; Robins, Richard J.

doi:10.1002/1439-7633(20020802)3:8<752::aid-cbic752>3.0.co;2-g

Cited by 32 publications

(39 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Analysis of long chain fatty acids by 2 H-{ 1 H} one-dimensional NMR in isotropic media is inadequate for the description of isotope redistribution coefficients since: (i) not all methylenic and ethylenic sites are resolved, and (ii) none of the large number of enantiotopic pro-R/S sites present can be observed (4,6,7,21,22). Such resolution is essential in interpreting hydrogen-atom origin, particularly in view of the domination of fatty acid biosynthesis by a series of enantioselective reactions (Fig.…”

mentioning

confidence: 99%

Investigation of Fatty Acid Elongation and Desaturation Steps in Fusarium lateritium by Quantitative Two-dimensional Deuterium NMR Spectroscopy in Chiral Oriented Media

Baillif

Robins

Feunteun

et al. 2009

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

The origin of hydrogen atoms during fatty acid biosynthesis in Fusarium lateritium has been quantified by isotope tracking close to natural abundance. Methyl linoleate was isolated from F. lateritium grown in natural abundance medium or in medium slightly enriched with labeled water, glucose, or acetate, and the 2 H incorporation was determined by quantitative 2 H-{ 1 H} NMR in isotropic and chiral oriented solvents. Thus, the individual ( 2 H/ 1 H) i ratio at each pro-R and pro-S hydrogen position of the CH 2 groups along the chain can be analyzed. These values allow the isotope redistribution coefficients (a ij ) that characterize the specific source of each hydrogen atom to be related to the nonexchangeable hydrogen atoms in glucose and to the medium water. In turn, these can be related to the stereoselectivity that operates during the introduction or removal of hydrogens along the fatty acid chain. First, at even CH 2 the pro-S hydrogen comes only from water by protonation, whereas the pro-R hydrogen is introduced partly via acetate but principally from water. Second, the nonexchangeable hydrogens of glucose (positions H-6,6 and H-1) are shown to be introduced to the odd CH 2 via the NAD(P)H pool used by both reductases involved in the elongation steps of the fatty acid chain. Third, it is proved that hydrogens removed at sites 9,10 and 12,13 during desaturation by ⌬ 9 -and ⌬ 12 -desaturases are pro-R, and that during these desaturation steps ␣-secondary kinetic isotope effects occur at the 9 and 12 positions and not at the 10 and 13 positions.Fatty acids are ubiquitous natural products involved in many key biological processes, including acting as components of membranes, as lipophilic modifiers, as fuel stores, and as precursors of intracellular messengers (1-3). Their biosynthesis, which is strictly conserved throughout higher organisms, can be separated into two parts as follows: the formation of the basic C16 unit, palmitoylCoA (C16:1), by the fatty-acid synthase complex (FAS) 2 and the subsequent modification of this chain by a range of elongases, desaturases, conjugases, hydroxylases, and epoxidases. Many of these steps involve stereoselective enzymatic reactions during which hydrogen atoms are inserted or eliminated.We have previously shown that this process leads to a distribution of 2 H in long chain fatty acids that is nonstatistical (4 -7). Thus, isotopic fractionation is seen to be introduced. Two features general to all organisms so far examined can be noted. First, the methylenic groups at even positions tend to be richer than those at odd positions. Second, one of the ethylenic groups present at the positions of desaturation is consistently impoverished relative to the methylenic sites, whereas the other is not.Thus, each hydrogen atom in the final product will have a ( 2 H/ 1 H) ratio that is representative of its initial origin, its passage through the FAS elongation steps, and its potential participation in post-elongation modification of the chain. To date, it has proved possible to exp...

show abstract

mentioning

confidence: 99%

Investigation of Fatty Acid Elongation and Desaturation Steps in Fusarium lateritium by Quantitative Two-dimensional Deuterium NMR Spectroscopy in Chiral Oriented Media

Baillif

Robins

Feunteun

et al. 2009

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…For sites 8,14 of methyl linoleate 2, ⌬(2 Ϫ P) is 10 ppm, which corresponds to 7% deviation. This difference appears large but is exaggerated by the high variation observed in both ( 2 H/ 1 H) 8 and ( 2 H/ 1 H) 14 measured on the products 6 V/L and 7 V/L (see Tables I and II) (8,29,31). This can satisfactorily be interpreted in terms of isotopic discrimination during chain elongation, the original source, and enzyme activity involved in the introduction of the different hydrogen atoms and isotopic selectivity during the desaturations (29,31,36,37).…”

Section: Resultsmentioning

confidence: 94%

“…Flash-chromatography on silica gel (19.8 g of mixed FAMEs) into polar and non-polar FAME fractions furnished methyl 1 g) of the following composition: methyl linoleate 2 (56.9%); methyl oleate 3 (17%); methyl stearate 4 (13.3%); and methyl palmitate 5 (12.8%). From this, methyl linoleate 2 (2.2 g) was isolated by argentation chromatography (29). FAMEs were recovered with 95% overall yield, and purity was confirmed by GC.…”

Section: Resultsmentioning

confidence: 99%

“…Mixed FAMEs (19.8 g) were separated using a column (30 ϫ 8 cm) and Silica Gel 60 (750 ml). The solvent gradient was used as follows: 2) The non-polar FAMEs were separated by modified argentation column chromatography as previously described (29). The separation of the FAME mixture (4.1 g) gave three fractions: 2 (2.2 g); 3 (0.77 g); and 1 The abbreviations used are: GC, gas chromatography; FAME, fatty acid methyl ester; ACP, acyl carrier protein; ERETIC, internal electronic reference signal (external reference to access internal concentrations); PC, phosphatidylcholine; TMU, N,N,NЈ,NЈ-tetramethylurea; COOMe, methyl ester group.…”

Section: Methodsmentioning

confidence: 99%

“…In view of the previous evidence that the 2 H isotopic patterns introduced into fatty acids by non-heme di-iron desaturases differ (29) and can be related to differences in biosynthetic pathways of fatty acid metabolism (8,30), the first step toward this comparison has been to compare the distribution of 2 H in vernolic acid and linoleic acid isolated from V. galamensis seed oil. In this report, it is shown that differences in the residual ( 2 H/ 1 H) patterns in these fatty acids may be related to the nature of the reaction catalyzed.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Quantitative Deuterium Isotopic Profiling at Natural Abundance Indicates Mechanistic Differences for Δ12-Epoxidase and Δ12-Desaturase in Vernonia galamensis

Billault

Duan

Guiet

et al. 2005

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Quantitative2 H NMR spectroscopy can determine the natural abundance ( 2 H/ 1 H) ratio at each site of a molecule. In natural products, variation in these values is related to the reaction mechanisms in the pertinent biosynthetic pathway. For the first time, this novel approach has been exploited to probe for mechanistic differences in the introduction of different functionalities into a long-chain fatty acid. Vernolic acid, a major component of the seed oil of Vernonia galamensis, contains both an epoxide and a desaturation. The site-specific isotopic distribution ( 2 H/ 1 H) i has been determined for both vernolic acid and linoleic acid isolated from the same V. galamensis oil. It is found that the ( 2 H/ 1 H) ratio of vernolic acid shows a pattern along the entire length of the chain, consistent with linoleic acid being its immediate precursor. Notably, the C13 relates to the C13 of linoleic acid but not to the C13 of oleic acid. Furthermore, the C12 and C13 positions in vernolic acid are less depleted, consistent with a change in hybridization state from sp 2 to sp 3 . However, the C11 position shows a marked relative enrichment in the vernolic acid, implying that it plays a role in the epoxidase but not the desaturase mechanism. Thus, although it can be concluded that the catalytic mechanisms for the epoxidase and desaturase activities are similar, marked differences in the residual ( 2 H/ 1 H) patterns indicate that the reaction mechanisms are not identical.

show abstract

Deuterium NMR of Liquid-crystalline Samples at Natural Abundance

Lesot

1996

eMagRes

View full text Add to dashboard Cite

Natural Deuterium Distribution in Fatty Acids Isolated from Peanut Seed Oil: A Site-Specific Study by Quantitative 2H NMR Spectroscopy

Cited by 32 publications

References 19 publications

Investigation of Fatty Acid Elongation and Desaturation Steps in Fusarium lateritium by Quantitative Two-dimensional Deuterium NMR Spectroscopy in Chiral Oriented Media

Investigation of Fatty Acid Elongation and Desaturation Steps in Fusarium lateritium by Quantitative Two-dimensional Deuterium NMR Spectroscopy in Chiral Oriented Media

Quantitative Deuterium Isotopic Profiling at Natural Abundance Indicates Mechanistic Differences for Δ12-Epoxidase and Δ12-Desaturase in Vernonia galamensis

Deuterium NMR of Liquid-crystalline Samples at Natural Abundance

Contact Info

Product

Resources

About