DXR

DXR reaction

The 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR, EC 1.1.1.267) is the second step in the MEP pathway that catalyses the production of 2-C-methyl-D-erythritol 4-phosphate (MEP) from 1-deoxy-D-xylulose 5-phosphate (DXP).

Modelling DXR

DXR is modelled reversible with the Michaelis-Menten rate law using Hanekom's generic random order bi-bi equation . There are a total of five kinetic parameters (2 forward Kms, 2 reverse Kms and 1 Kcat), and one thermodynamic parameter (Equilibrium constant , Keq).

$V_\mathrm{DXR}= \cfrac{Kcat_\mathrm{forward} \bullet [DXR] \bullet \left(\cfrac{[DXP]}{Km_\mathrm{dxp}}\right) \bullet \left( \cfrac{[NADPH]}{Km_\mathrm{nadph}} \right) \bullet \left( 1 - \cfrac{\cfrac{[DXP]\cdot[NADPH]}{[MEP]\cdot[NADP]}}{Keq}\right)}{\left(1 +\cfrac{[DXP]}{Km_\mathrm{dxp}} + \cfrac{[NADP]}{Km_\mathrm{nadp}}\right) \bullet \left( 1 + \cfrac{[NADPH]}{Km_\mathrm{nadph}} + \cfrac{[MEP]}{Km_\mathrm{mep}}\right)}$