Biophysical properties of PFV and SFVmac PR-RT. (A) Far UV circular dichroism (CD) spectra of wild-type SFVmac (continuous line) and PFV PR-RT (dotted line) were acquired at 20°C using a band width of 1 nm, a sensitivity of 100 mdeg and a data density of 5 points/nm in a 0.1 cm cell with 0.5 μM of each enzyme in 25 mM Na2HPO4/NaH2PO4 pH 7.4, and 5 mM NaCl. (B) Size exclusion chromatography of PFV PR-RT using an S200 HR 10/30 column. The run was performed with 10 nmol PFV PR-RT in 50 mM Na2HPO4/NaH2PO4 pH 7.4, 300 mM NaCl and 0.5 mM DTT. The inset shows the fit to the data obtained for the molecular masses of the standard proteins (open circles), which was used for the determination of the molecular mass of PFV PR-RT (closed circle).