title: The kinetics and regulation of phosphofructokinase from Teladorsagia circumcincta.
abstract: Phosphofructokinase (PFK-1) activity was examined in L(3) and adult Teladorsagia circumcincta, both of which exhibit oxygen consumption. Although activities were higher in the adult stage, the kinetic properties of the enzyme were similar in both life cycle stages. T. circumcincta PFK-1 was subject to allosteric inhibition by high ATP concentration, which increased both the Hill coefficient (from 1.4±0.2 to 1.7±0.2 in L(3)s and 2.0±0.3 to 2.4±0.4 in adults) and the K(½) for fructose 6 phosphate (from 0.35±0.02 to 0.75±0.05mM in L(3)s and 0.40±0.03 to 0.65±0.05mM in adults). The inhibitory effects of high ATP concentration could be reversed by fructose 2,6 bisphosphate and AMP, but glucose 1,6 bisphosphate had no effect on activity. Similarly, phosphoenolpyruvate had no effect on activity, while citrate, isocitrate and malate exerted mild inhibitory effects, but only at concentrations exceeding 2mM. The observed kinetic properties for T. circumcincta PFK-1 were very similar to those reported for purified Ascaris suum PFK-1, though slight differences in sensitivity to ATP concentration suggests there may be subtle variations at the active site. These results are consistent with the conservation of properties of PFK-1 amongst nematode species, despite between species variation in the ability to utilise oxygen.
authors.affiliation: Institute of Food Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
authors.forename: L R
authors.initials: LR
authors.lastname: Walker
authors.forename: D C
authors.initials: DC
authors.lastname: Simcock
authors.forename: K C
authors.initials: KC
authors.lastname: Pedley
authors.forename: H V
authors.initials: HV
authors.lastname: Simpson
authors.forename: S
authors.initials: S
authors.lastname: Brown
mesh_terms: D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D019343:Citric Acid / Q000494:pharmacology; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005635:Fructosediphosphates / Q000494:pharmacology; D005636:Fructosephosphates / Q000378:metabolism; D007523:Isocitrates / Q000494:pharmacology; D007700:Kinetics; D007814:Larva / Q000201:enzymology; D008293:Malates / Q000494:pharmacology; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D012756:Sheep; D014251:Trichostrongyloidea / Q000201:enzymology*
chemical_list: D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D005635:Fructosediphosphates; D005636:Fructosephosphates; D007523:Isocitrates; D008293:Malates; D019343:Citric Acid; D000249:Adenosine Monophosphate; C027618:fructose-6-phosphate; C027652:fructose 2,6-diphosphate; C030298:malic acid; D000255:Adenosine Triphosphate; C034219:isocitric acid; D010732:Phosphofructokinase-1