Kinetic studies on the reaction catalysed by phosphofructokinase from Trypanosoma brucei.
The steady-state kinetics of the reaction catalysed by the bloodstream form of Trypanosoma brucei were studied at pH 6.7. In the presence of 50 mM-potassium phosphate buffer, the apparent co-operativity with respect to fructose 6-phosphate and the non-linear relationship between initial velocity and enzyme concentration, which were found when the enzyme was assayed in 50 mM-imidazole buffer [Cronin & Tipton (1985) Biochem. J. 227, 113-124], are not evident. Studies on the variations of the initial rate with changing concentrations of MgATP and fructose 6-phosphate, the product inhibition by fructose 1,6-bisphosphate and the effects of the alternative substrate ITP were consistent with an ordered reaction pathway, in which MgATP binds to the enzyme before fructose 6-phosphate, and fructose 1,6-bisphosphate is the first product to dissociate from the ternary complex.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D005635:Fructosediphosphates / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D007293:Inosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
D005635:Fructosediphosphates; D007293:Inosine Triphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1; C029063:fructose-1,6-diphosphate