Glycerol gradient sedimentation of a mixture of MsmPolD2, catalase, BSA and cytochrome c was performed as described under Experimental Procedures. (A) Aliquots (15 µl) of the odd-numbered gradient fractions were analyzed by SDS-PAGE. The Coomassie Blue-stained gel is shown. (B) Polymerase reaction mixtures (20 µl) containing 50 mM Tris-HCl (pH 8.0), 1.25 mM CoCl2, 1 pmol of 32P-labeled primer-template DNA substrate, 100 µM each of dATP, dGTP, dCTP and dTTP, and 2 µl of the odd-numbered gradient fractions were incubated for 10 min at 37°C. The reaction products were resolved by PAGE and visualized by autoradiography.