Isomers of conjugated linoleic acids are synthesized via different mechanisms in ruminal digesta and bacteria

R. John Wallace, Nest McKain, Kevin J. Shingfield, Estelle Devillard

Research output: Contribution to journalArticle

123 Citations (Scopus)

Abstract

Digesta samples from the ovine rumen and pure ruminal bacteria were incubated with linoleic acid (LA) in deuterium oxide-containing buffer to investigate the mechanisms of the formation of conjugated linoleic acids (CLAs). Rumenic acid (RA; cis-9,trans-11-18:2), trans-9,trans-11-18:2, and trans-10,cis-12-18:2 were the major CLA intermediates formed from LA in ruminal digesta, with traces of trans-9, cis-11-18:2, cis-9, cis-11-18: 2, and cis-10,cis-12-18:2. Mass spectrometry indicated an increase in the n+1 isotopomers of RA and other 9,11-CLA isomers, as a result of labeling at C-13, whereas 10,12 isomers contained minimal enrichment. In pure culture, Butyrivibrio fibrisolvens and Clostridium proteoclasticum produced mostly RA with minor amounts of other 9,11 isomers, all labeled at C-13. Increasing the deuterium enrichment in water led to an isotope effect, whereby 1 H was incorporated in preference to 2 H. In contrast, the type strain and a ruminal isolate of Propionibacterium acnes produced trans-10,cis-12-18: 2 and other 10,12 isomers that were minimally labeled. Incubations with ruminal digesta provided no support for ricinoleic acid (12-OH,cis-9-18:1) as an intermediate of RA synthesis. We conclude that geometric isomers of 10,12-CLA are synthesized by a mechanism that differs from the synthesis of 9,11 isomers, the latter possibly initiated by hydrogen abstraction on C-11 catalyzed by a radical intermediate enzyme.

Original languageEnglish
Pages (from-to)2247-2254
Number of pages8
JournalJournal of Lipid Research
Volume48
Issue number10
DOIs
Publication statusPublished - Oct 2007

Keywords

  • biohydrogenation
  • butyrivibrio fibrisolvens
  • clostridium proteoclasticum
  • propionibacterium acnes
  • rumenic acid
  • unsaturated fatty-acids
  • butyrivibrio-fibrisolvens
  • milk-fat
  • lactobacillus-acidophilus
  • cancer-cells
  • dairy-cows
  • fish-oil
  • rumen
  • identification

Cite this

Isomers of conjugated linoleic acids are synthesized via different mechanisms in ruminal digesta and bacteria. / Wallace, R. John; McKain, Nest; Shingfield, Kevin J.; Devillard, Estelle.

In: Journal of Lipid Research, Vol. 48, No. 10, 10.2007, p. 2247-2254.

Research output: Contribution to journalArticle

Wallace, R. John ; McKain, Nest ; Shingfield, Kevin J. ; Devillard, Estelle. / Isomers of conjugated linoleic acids are synthesized via different mechanisms in ruminal digesta and bacteria. In: Journal of Lipid Research. 2007 ; Vol. 48, No. 10. pp. 2247-2254.
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abstract = "Digesta samples from the ovine rumen and pure ruminal bacteria were incubated with linoleic acid (LA) in deuterium oxide-containing buffer to investigate the mechanisms of the formation of conjugated linoleic acids (CLAs). Rumenic acid (RA; cis-9,trans-11-18:2), trans-9,trans-11-18:2, and trans-10,cis-12-18:2 were the major CLA intermediates formed from LA in ruminal digesta, with traces of trans-9, cis-11-18:2, cis-9, cis-11-18: 2, and cis-10,cis-12-18:2. Mass spectrometry indicated an increase in the n+1 isotopomers of RA and other 9,11-CLA isomers, as a result of labeling at C-13, whereas 10,12 isomers contained minimal enrichment. In pure culture, Butyrivibrio fibrisolvens and Clostridium proteoclasticum produced mostly RA with minor amounts of other 9,11 isomers, all labeled at C-13. Increasing the deuterium enrichment in water led to an isotope effect, whereby 1 H was incorporated in preference to 2 H. In contrast, the type strain and a ruminal isolate of Propionibacterium acnes produced trans-10,cis-12-18: 2 and other 10,12 isomers that were minimally labeled. Incubations with ruminal digesta provided no support for ricinoleic acid (12-OH,cis-9-18:1) as an intermediate of RA synthesis. We conclude that geometric isomers of 10,12-CLA are synthesized by a mechanism that differs from the synthesis of 9,11 isomers, the latter possibly initiated by hydrogen abstraction on C-11 catalyzed by a radical intermediate enzyme.",
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author = "Wallace, {R. John} and Nest McKain and Shingfield, {Kevin J.} and Estelle Devillard",
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T1 - Isomers of conjugated linoleic acids are synthesized via different mechanisms in ruminal digesta and bacteria

AU - Wallace, R. John

AU - McKain, Nest

AU - Shingfield, Kevin J.

AU - Devillard, Estelle

PY - 2007/10

Y1 - 2007/10

N2 - Digesta samples from the ovine rumen and pure ruminal bacteria were incubated with linoleic acid (LA) in deuterium oxide-containing buffer to investigate the mechanisms of the formation of conjugated linoleic acids (CLAs). Rumenic acid (RA; cis-9,trans-11-18:2), trans-9,trans-11-18:2, and trans-10,cis-12-18:2 were the major CLA intermediates formed from LA in ruminal digesta, with traces of trans-9, cis-11-18:2, cis-9, cis-11-18: 2, and cis-10,cis-12-18:2. Mass spectrometry indicated an increase in the n+1 isotopomers of RA and other 9,11-CLA isomers, as a result of labeling at C-13, whereas 10,12 isomers contained minimal enrichment. In pure culture, Butyrivibrio fibrisolvens and Clostridium proteoclasticum produced mostly RA with minor amounts of other 9,11 isomers, all labeled at C-13. Increasing the deuterium enrichment in water led to an isotope effect, whereby 1 H was incorporated in preference to 2 H. In contrast, the type strain and a ruminal isolate of Propionibacterium acnes produced trans-10,cis-12-18: 2 and other 10,12 isomers that were minimally labeled. Incubations with ruminal digesta provided no support for ricinoleic acid (12-OH,cis-9-18:1) as an intermediate of RA synthesis. We conclude that geometric isomers of 10,12-CLA are synthesized by a mechanism that differs from the synthesis of 9,11 isomers, the latter possibly initiated by hydrogen abstraction on C-11 catalyzed by a radical intermediate enzyme.

AB - Digesta samples from the ovine rumen and pure ruminal bacteria were incubated with linoleic acid (LA) in deuterium oxide-containing buffer to investigate the mechanisms of the formation of conjugated linoleic acids (CLAs). Rumenic acid (RA; cis-9,trans-11-18:2), trans-9,trans-11-18:2, and trans-10,cis-12-18:2 were the major CLA intermediates formed from LA in ruminal digesta, with traces of trans-9, cis-11-18:2, cis-9, cis-11-18: 2, and cis-10,cis-12-18:2. Mass spectrometry indicated an increase in the n+1 isotopomers of RA and other 9,11-CLA isomers, as a result of labeling at C-13, whereas 10,12 isomers contained minimal enrichment. In pure culture, Butyrivibrio fibrisolvens and Clostridium proteoclasticum produced mostly RA with minor amounts of other 9,11 isomers, all labeled at C-13. Increasing the deuterium enrichment in water led to an isotope effect, whereby 1 H was incorporated in preference to 2 H. In contrast, the type strain and a ruminal isolate of Propionibacterium acnes produced trans-10,cis-12-18: 2 and other 10,12 isomers that were minimally labeled. Incubations with ruminal digesta provided no support for ricinoleic acid (12-OH,cis-9-18:1) as an intermediate of RA synthesis. We conclude that geometric isomers of 10,12-CLA are synthesized by a mechanism that differs from the synthesis of 9,11 isomers, the latter possibly initiated by hydrogen abstraction on C-11 catalyzed by a radical intermediate enzyme.

KW - biohydrogenation

KW - butyrivibrio fibrisolvens

KW - clostridium proteoclasticum

KW - propionibacterium acnes

KW - rumenic acid

KW - unsaturated fatty-acids

KW - butyrivibrio-fibrisolvens

KW - milk-fat

KW - lactobacillus-acidophilus

KW - cancer-cells

KW - dairy-cows

KW - fish-oil

KW - rumen

KW - identification

U2 - 10.1194/jlr.M700271-JLR200

DO - 10.1194/jlr.M700271-JLR200

M3 - Article

VL - 48

SP - 2247

EP - 2254

JO - Journal of Lipid Research

JF - Journal of Lipid Research

SN - 0022-2275

IS - 10

ER -