Fructose 1,6 bisphosphate aldolase

This enzyme splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are Dihydroxyacetone phosphate (DHAP) and Glyceraldehyde 3-phosphate (Gly3P).

Chemical equation

$Fru1,6BP \rightleftharpoons Gly3P + DHAP$

Rate equation

Reversible Uni-Bi Michaelis-Menten is used.

$\frac{V_{mf} \frac{[Fru1,6BP]}{K_{Fru1,6BP}} - V_{mr}\frac{[DHAP][G3P]}{K_{DHAP}K_{Gly3P}} }{1 + \frac{[Fru1,6BP]}{K_{Fru1,6BP}} + \frac{[DHAP]}{K_{DHAP}} +\frac{[Gly3P]}{K_{Gly3P}} + \frac{[DHAP][Gly3P]}{K_{DHAP}K_{Gly3P}} }$

Modified rate law to take into consideration the equilibrium constant

$\frac{V_{mf} \frac{[Fru1,6BP]}{K_{Fru1,6BP}} \left(1- \frac{[DHAP][Gly3P]}{K_{eq}[Fru1,6BP]} \right)}{1 + \frac{[Fru1,6BP]}{K_{Fru1,6BP}} + \frac{[DHAP]}{K_{DHAP}} +\frac{[Gly3P]}{K_{Gly3P}} + \frac{[DHAP][Gly3P]}{K_{DHAP}K_{Gly3P}} }$

Parameters

Parameter	Value	Units	Organism	Remarks
$V_{mf}$	0.08	$mM \times min^{-1}$	Hela cell line
$V_{mr}$	0.063	$mM \times min^{-1}$	Rodent AS-30D hepatoma
$Km_{Fru1,6BP}$	0.009	mM	Hela cell line
$Km_{Gly3P}$	0.16	mM	Rodent AS-30D hepatoma
$Km_{DHAP}$	0.08	mM	Rodent AS-30D hepatoma

Parameters with uncertainty

• The value for $V_{mf}$ is collected from Hernandez et. al. . The $V_{mr}$ is calcualted from the sampled $V_{mr}$, $Km_{Gly3P}$, $Km_{DHAP}$ and $K_{eq}$ values using the Haldane equation. Alternatively the reported value from AS-30D can be considered. The standard deviation can be calculated based on the same ratio of $V_{mf}$. However, as it is from a different species an extra 20% of uncertainty will be added. This gives the value $V_{mf}=0.063 \pm 0.028$

• The value for $Km_{Fru1,6BP}, Km_{Gly3P}, Km_{DHAP}$ are collected from Ali D. Malay et. al. for wildtype Aldolase B gene at $30^{\circ}$C.

Parameter	Value	Units	Organism	Remarks
$V_{mf}$	$0.2 \pm 0.05 (5)$ Failed to parse (Cannot store math image on filesystem.): 0.08 \pm 0.02	$U\cdot(\text{mg protein})^{-1}$ $mM \times min^{-1}$	Hela cell line
$V_{mr}$	Sampled based on Haldane equation. Alternative:$0.063 \pm 0.028$	$U\cdot(\text{mg protein})^{-1}$
$Km_{Fru1,6BP}$	$0.0024 \pm 0.0004$	mM	Human cell
$Km_{Gly3P}$	$0.48 \pm 0.15$	mM	Human cell
$Km_{DHAP}$	$0.38 \pm 0.01$	mM	Human cell

Equilibrium constant

Equilibrium constant	Conditions	Source
0.10	pH=7, T=25°C	Voet et al. from Newshole et al. (1973) p 97: $\Delta G' = 22.8\ kJ.mol^{-1}$, Failed to parse (Cannot store math image on filesystem.): Keq = exp(-\frac{\Delta G'}{RT}) = exp(\frac{-22800}{8.31*298.15}) \approx 0.00010
0.067	pH=7, T=25°C	Lehninger, (1975) p 407: $\Delta G' = 23.8\ kJ.mol^{-1}$, Failed to parse (Cannot store math image on filesystem.): Keq = exp(-\frac{\Delta G'}{RT}) = exp(\frac{-23800}{8.31*298.15}) \approx 6.7326E-005

• Taking average of these two values give Failed to parse (Cannot store math image on filesystem.): 8.40E-005 \pm 0.000023