IMPDHbt (A) and IMPDHlpp (B) activities versus NAD concentration.

<p>Enzyme activity was determined at a fixed concentration of IMP (1 mM for IMPDHbt and 2 mM for IMPDHlpp), and in the absence (red curve) or in the presence (blue curve) of 5 mM MgATP. The curves correspond to the fit of the experimental data to the Michaelis-Menten equation and the calculated parameters are displayed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116578#pone.0116578.t004" target="_blank">Table 4</a>.