Enzyme-to-enzyme channelling of Krebs cycle metabolic intermediates in Caco-2 cells exposed to [2-13c]propionate

Biochem J. 1996 Aug 1;317 ( Pt 3)(Pt 3):861-3. doi: 10.1042/bj3170861.


The generation of 13C-labelled lactate by colon carcinoma cells of the Caco-2 line incubated for 120 min in the presence of [2-13C]propionate (10 mM) was assessed by 13C NMR. About 10% of the total amount of 13C-labelled lactate was recovered in the cell pellet and displayed a [2-13C]lactate/[3-13C]lactate isotopomer ratio of 1.18 +/- 0.01. An even higher isotopomer ratio of 1.53 +/- 0.14 was observed in the case of 13C-labelled lactate released by the cells into the incubation medium. These findings indicate that, in the Caco-2 cells, metabolic intermediates of the Krebs cycle undergo enzyme-to-enzyme channelling in the sequence of reactions catalysed by succinyl-CoA synthetase, succinate dehydrogenase and fumarase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Caco-2 Cells / metabolism*
  • Carbon Isotopes
  • Citric Acid Cycle*
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology
  • Humans
  • Magnetic Resonance Spectroscopy
  • Propionates / pharmacology*


  • Carbon Isotopes
  • Propionates
  • propionic acid