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The tricarboxylic acid cycle in L3 Teladorsagia circumcincta: metabolism of acetyl CoA to succinyl CoA

journal contribution
posted on 2023-05-17, 10:18 authored by Simcock, DC, Walker, LR, Pedley, KC, Simpson, HV, Brown, S
Nematodes, like other species, derive much of the energy for cellular processes from mitochondrial pathways including the TCA cycle. Previously, we have shown L3 Teladorsagia circumcincta consume oxygen and so may utilise a full TCA cycle for aerobic energy metabolism. We have assessed the relative activity levels and substrate affinities of citrate synthase, aconitase, isocitrate dehydrogenase (both NAD+ and NADP+ specific) and α-ketoglutarate dehydrogenase in homogenates of L3 T. circumcincta. All of these enzymes were present in homogenates. Compared with citrate synthase, low levels of enzyme activity and low catalytic efficiency was observed for NAD+ isocitrate dehydrogenase and especially α-ketoglutarate dehydrogenase. Therefore, it is likely that the activity of these to enzymes regulate overall metabolite flow through the TCA cycle, especially when [NAD+] limits enzyme activity. Of the enzymes tested, only citrate synthase had substrate affinities which were markedly different from values obtained from mammalian species. Overall, the results are consistent with the suggestion that a full TCA cycle exists within L3 T. circumcincta. While there may subtle variations in enzyme properties, particularly for citrate synthase, the control points for the TCA cycle in L3 T. circumcincta are probably similar to those in the tissues of their host species.


Publication title

Experimental Parasitology








School of Health Sciences


Orlando, FL : Academic Press

Place of publication


Rights statement

Copyright 2011 Elsevier Inc.

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