β-oxing

Dietary fibres are fermented by bacteria in the colon to form short-chain fatty acids: acetate (C2), propionate (C3) and butyrate (C4). Fatty acids are taken up by colonocytes, and processed in the mitochondria using β-oxidation. This metabolism of — otherwise indigestible — carbohydrates via gut flora provides a major source of energy in humans.

Those of you interested in SCFA metabolism would do well to follow the work of Barbara Bakker [1-3]. In a recent paper with Karen van Eunen and friends, Babs created a mathematical model of β-ox in the rat liver. The model considers competition between acyl-CoAs with differing chain lengths for the same enzymes, which can lead to pathway saturation. I’ve created SBML versions of their model: have a play.


overview of β-ox [1]

References

  1. van Eunen K, Simons SM, Gerding A, Bleeker A, den Besten G, Touw CM, Houten SM, Groen BK, Krab K, Reijngoud DJ, Bakker BM (2013) “Biochemical competition makes fatty-acid β-oxidation vulnerable to substrate overload” PLoS Computational Biology 9:e1003186.
    doi:10.1371/journal.pcbi.1003186
  2. den Besten G, van Eunen K, Groen AK, Venema K, Reijngoud DJ, Bakker BM (2013) “The role of short-chain fatty acids in the interplay between diet, gut microbiota, and host energy metabolism” Journal of Lipid Research 54:2325-2340.
    doi:10.1194/jlr.R036012
  3. den Besten G, Lange K, Havinga R, van Dijk TH, Gerding A, van Eunen K, Müller M, Groen AK, Hooiveld GJ, Bakker BM, Reijngoud DJ (2013) “Gut-derived short-chain fatty acids are vividly assimilated into host carbohydrates and lipids” American Journal of Physiology – Gastrointestinal and Liver Physiology 305:G900-910.
    doi:10.1152/ajpgi.00265.2013
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