Simulation of Sym/Sub U with UTP. (A) Hypothesized mechanism used for simulation. E=Enzyme, R
=Template/Primer RNA, ER
=active complex. The nonvarying parameters were: ER
: 500 nM, NTPs: 750 or 1500 μM, k+1 : 10 μM-1 sec-1 and k
: 5 × 104 sec-1. In the simulation, which is based on the mechanism in . k
and k-1 (both in gray) were varied. (B) Data and simulated fit. Experimentally derived products formed with 750 (dark gray circles/blue) or 1500 μM (light gray circles/orange) UTP were plotted as a function of time (in seconds). Simulated fits (curves) were superimposed with same color scheme.