Regulation of the fructose 6-phosphate/fructose 2,6-bisphosphate cycle by enzyme phosphorylation and sn-glycerol 3-phosphate.
The regulation of the Fru-6-P/Fru-2,6-P2 cycle by the cooperation of allosteric and covalent mechanisms was investigated in a reconstituted enzyme system under in vitro conditions. Phosphorylation of the bifunctional enzyme exerts a much stronger effect than sn-glycerol 3-phosphate in lowering the quasi-stationary concentration of fructose 2,6-bisphosphate and in increasing the critical concentration of the fructose phosphates, respectively. However, sn-glycerol 3-phosphate is able to strongly amplify the decrease of the quasi-stationary concentration of fructose 2,6-bisphosphate due to phosphorylation. The experiments can be described by a mathematical model involving rate equations for the dephosphorylated and the phosphorylated PFD-2 and FBPase-2. The results are compared with data from the literature obtained under in vivo conditions.
Frenzel
J
J
Institut für Biochemie, Bereich Medizin, Universität Leipzig.
Schellenberger
W
W
Eschrich
K
K
Hofmann
E
E
D000818:Animals; D005635:Fructosediphosphates / Q000378:metabolism*; D005636:Fructosephosphates / Q000378:metabolism*; D005994:Glycerophosphates / Q000494:pharmacology; D007700:Kinetics; D008954:Models, Biological; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats
D005635:Fructosediphosphates; D005636:Fructosephosphates; D005994:Glycerophosphates; C027618:fructose-6-phosphate; C027652:fructose 2,6-diphosphate; C029620:alpha-glycerophosphoric acid; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases