FIG. 4.
Steady-state kinetics of ribavirin and viramidine 5′-monophosphorylation catalyzed by cN-II. In the assay, the IMP concentration was set at 4 mM, with [5-14C]ribavirin or [5-14C]viramidine concentration varied from 12.5 to 500 μM. The initial velocity at various substrate concentrations was fitted into Michaelis-Menten equations for calculation of Km and kcat values. •: ribavirin as a substrate. ▪: viramidine as a substrate. All the data points are the average of at least three experiments and are presented as mean ± standard deviation. (A) In the presence of 2 mM ATP; (B) in the presence of 0.4 mM BPG.