Adenylate kinase

Adenylate kinase is a phosphotransferase enzyme that catalyzes the interconversion of adenine nucleotides.

Chemical equation

$ATP + AMP \rightleftharpoons 2ADP$

Rate equation

Reversible mass action rate law is used

$K_{1}[ATP][AMP] - K_{2}[ADP]^2$

Parameter values

Parameter	Value	Organism	Remarks
$K_{1}$	1	HeLa cell line
$K_{2}$	2.26

Parameters with uncertainty

Parameter

Value

$K_1=1 \pm 0.04$, $K_2=2.26 \pm 0.09044$

The Adenylate kinase was modeled using mass action kinetics with parameters $K_1$ and $K_2$ consistent with the equilibrium constant of the reaction. The equilibrium constant (Keq=2.26) is from Bergmeyer H.U. (1974) page 486: $Keq(ATP+AMP \rightarrow 2*ADP, pH=7.4, T=25^oC)=2.26$ In Mass action rate law the relationship is $\frac{K_2}{K_1} = K_{eq}$. Considering $K_{eq} = 2.26$ we have $K_2=2.26$ and $K_1 = 1$ to be consistent with the equation. The value of $K_1$ and $K_2$ would be varied based on the uncertainty on $K_{eq}$ value mentioned in the following table. The percentage of error in Keq is $\approx 4$. With similar percent of error the value for $K_1 = 1 \pm 0.04$ and $K_2 = 2.26 \pm 0.09044$

Equilibrium constant

Equilibrium constant	Conditions	Source
0.48+/-0.015 (mean+/-SEM; n=7)	pH=7, T=25°C, 10mM Mg2+	NIST database "Thermodynamics of Enzyme-Catalyzed Reactions" entry [61ATK/BUR_640] from Atkinson et al. (1961) Table 2 Therefore, Keq(forward) = 0.48 +/-0.015 (n=7; mean+/-SEM calculated from individual measurements).