Phosphofructokinase from liver of the rainbow trout, Oncorhynchus mykiss.
Phosphofructokinase (PFK) from liver of the rainbow trout Oncorhynchus mykiss was purified to homogeneity with a recovery of 35% of total activity. The purified enzyme was a homotetramer with a native molecular weight of 297,000 +/- 16,000 and a subunit M(r) of 76,000 +/- 3000. Arrhenius plots of enzyme activity were linear over 5-27 degrees C with an activation energy of 52.3 +/- 2.1 kJ/mol. The binding of fructose 6-phosphate was cooperative. High ATP increased the Hill coefficient and produced a marked allotropic inhibition of the enzyme activity. The affinity of the enzyme for fructose 6-phosphate was increased by the addition of the enzyme activators such as inorganic phosphate, ammonium ions, AMP, and fructose 2,6-bisphosphate; the activators also reduced the inhibitory effect of ATP. Trout liver PFK was activated by phosphoenolpyruvate at physiological concentrations but was not affected by citrate.
Su
J Y
JY
Department of Chemistry, Carleton University, Ottawa, Ontario, Canada.
Storey
K B
KB
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000641:Ammonia / Q000494:pharmacology; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D005635:Fructosediphosphates / Q000494:pharmacology; D005636:Fructosephosphates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000201:enzymology*; D046911:Macromolecular Substances; D008970:Molecular Weight; D010710:Phosphates / Q000494:pharmacology; D010732:Phosphofructokinase-1 / Q000737:chemistry / Q000378:metabolism*; D013816:Thermodynamics; D014337:Trout / Q000378:metabolism*
D005635:Fructosediphosphates; D005636:Fructosephosphates; D046911:Macromolecular Substances; D010710:Phosphates; D000249:Adenosine Monophosphate; C027618:fructose-6-phosphate; D000641:Ammonia; C027652:fructose 2,6-diphosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1