Expression and purification of a functional human hepatitis B virus polymerase

Figure 4 Enzyme activity assay of recombinant hepatitis B virus polymerase. Comparison of enzyme activities between hepatitis B virus polymerase (HBV-Pol) from Escherichia coli expression system (P-E) and in vitro expression system (P-R). DNA-dependent DNA polymerase (DDDP) activity and RNA-dependent DNA polymerase (RDDP) activity of the P-E and P-R were monitored under standard conditions. All endogenous DDDP activities were suppressed by 60 mmol/L aphidicolin and 1 mmol/L NEM (A and B). The effects of increasing concentrations of adenosine triphosphate (ATP) are shown in C. DDDP activity using poly (dA) • oligo (dT)_12-18 and RDDP activity using poly (rA) • oligo (dT)_12-18 were used as the substrate for DDDP activity and RDDP activity assays, respectively. CPM: Counts per minute.