Nematodes which have adapted to an anaerobic lifestyle in their adult stages oxidise phosphoenolpyruvate (PEP) to oxaloacetate rather than pyruvate as the final product of glycolysis. This adaptation involves selective expression of the enzyme phosphoenolpyruvate carboxykinase (PEPCK), instead of pyruvate kinase (PK). However, such adaptation is not absolute in aerobic nematode species. We have examined the activity and kinetics of PEPCK and PK in larvae (L₃) and adults of Teladorsagia circumcincta, a parasite known to exhibit oxygen uptake. Results revealed that PK and PEPCK activity existed in both L₃s and adults. The enzymes had differing affinity for nucleotide diphosphates: while both can utilise GDP, only PK utilised ADP and only PEPCK utilised IDP. In both life cycle stages, enzymes showed similar affinity for PEP. PK activity was predominant in both stages, although activity of this enzyme was lower in adults. When combined, both the activity levels and the enzyme kinetics showed that pyruvate production is probably favoured in both L₃ and adult stages of T. circumcincta and suggest that metabolism of PEP to oxaloacetate is a minor metabolic pathway in this species.

Item Type:	Refereed Article
Keywords:	phosphoenolpyruvate carboxykinase, pyruvate kinase, nematode, Teladorsagia circumcincta, energy metabolism
Research Division:	Biological Sciences
Research Group:	Biochemistry and Cell Biology
Research Field:	Enzymes
Objective Division:	Animal Production and Animal Primary Products
Objective Group:	Livestock Raising
Objective Field:	Sheep - Meat
UTAS Author:	Brown, S (Dr Simon Brown)
ID Code:	82444
Year Published:	2012
Web of Science® Times Cited:	2
Deposited By:	Health Sciences A
Deposited On:	2013-02-04
Last Modified:	2015-02-02
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