Phosphofructokinase type 1

The enzyme Phosphofructokinase Type-1 uses another ATP molecule to transfer a phosphate group to Fru6P to form fructose 1, 6-bisphosphate. PFK-1 is an allosteric enzyme showing cooperative behaviour with Fru6P and hyperbolic kinetics with ATP.

Chemical equation

$Fru6P + ATP \rightleftharpoons Fru1,6BP + ADP$

Rate equation

The concerted transition model of Monod, Wyman and Changeux (MWC model) is used as a rate equation for this tetrameric enzyme for considering exclusive ligand binding (F6P, activators and inhibitors) together with mixed type activation, (Fru2,6BP or AMP or Pi) .

$v = Vm_r\left (\left (\frac{\frac{[ATP]}{Km_{ATP}}}{1 + \frac{[ATP]}{Km_{ATP}} }\right ) \left ( \frac{ 1 + \frac{[\beta Fru2,6BP]}{ \alpha Ka_{Fru2,6BP} } }{ 1 + \frac{[Fru2,6BP]}{ \alpha Ka_{Fru2,6BP} } } \right ) \left( \frac{\frac{[Fru6P]\left(1+\frac{[Fru2,6BP]}{[\alpha Ka_{Fru2,6BP}]}\right)}{Km_{Fru6P}\left(1 + \frac{[Fru2,6BP]}{Ka_{Fru2,6BP}}\right)} \left[1 + \frac{[Fru6P]\left(1+\frac{[Fru2,6BP]}{\alpha Ka_{Fru2,6BP}}\right)}{Km_{Fru6P\left(1 + \frac{[Fru2n6BP]}{Ka_{Fru2,6BP}}\right)}} \right]^3} { \frac{L\left( 1 + \frac{[CIT]}{Ki_{CIT}}\right)^4\left(1 + \frac{[ATP]}{Ki_{ATP}}\right)^4}{\left(1+\frac{[Fru2,6BP]}{Ka_{Fru2,6BP}}\right)^4} + \left[1 + \frac{Fru6P\left(1+\frac{Fru2,6BP}{\alpha Ka_{Fru2,6BP}}\right)}{Km_{Fru6P\left(1 + \frac{[Fru2n6BP]}{Ka_{Fru2,6BP}}\right)}} \right]^4 } \right) - \left( \frac{\frac{[ADP][F1,6BP]}{K_{ADP}K_{F1,6BP}K_{eq}}}{\frac{[ADP]}{K_{ADP}} + \frac{[Fru1,6BP]}{K_{Fru1,6BP}} + \frac{[ADP][Fru1,6BP]}{K_{ADP}K_{Fru1,6BP}} + 1 } \right) \right)$

Parameter values

Parameter	Value	Organism	Remarks
$Vm_{r}$	0.078	HeLa cell line	Moreno-Sánchez, Marín-Hernández, Encalada & Saavedra, unpublished results
$Km_{Fru6P}$	1.0
$Km_{ATP}$	0.021
$Ki_{ATP}$	20
$Ki_{CIT}$	6.8
$Ka_{Fru2,6BP}$	$8.4 \times 10^{-4}$
$\alpha$	0.32
$\beta$	0.98
$L$	4.1
$K_{ADP}$	5
$K_{Fru1,6BP}$	5