Enzyme-to-enzyme channelling of Krebs cycle metabolic intermediates in Caco-2 cells exposed to [2-13c]propionate.
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.
Malaisse
W J
WJ
Laboratory of Experimental Medicine, Brussels Free University (ULB), Belgium.
Zhang
T M
TM
Verbruggen
I
I
Willem
R
R
D018938:Caco-2 Cells / Q000378:metabolism*; D002247:Carbon Isotopes; D002952:Citric Acid Cycle; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D011422:Propionates / Q000494:pharmacology*
D002247:Carbon Isotopes; D011422:Propionates; C029658:propionic acid