Purification and activity of T4 RNA Ligase 2 truncated mutants .  (A)  Aliquots of T4 RNA ligase 2 truncated and mutants were separated on 10-20% Tris-glycine SDS polyacrylamide gels and stained with Coomassie blue. The size (in kDa) of marker polypeptides are indicated on the left.  (B)  Intermolecular strand-joining activity of T4 RNA ligase 2 truncated mutants under multiple turnover conditions. 10 pmol 5'-adenylated 17-mer DNA was incubated for one hour at 25°C with 5 pmol 5'- FAM-labeled 31-mer RNA. 1 pmol of each ligase was added into reaction mixture. The reaction products were resolved on denaturing 15% acrylamide gels, scanned and quantified as described in the methods section. Rnl2tr = T4 RNA ligase 2 truncated, Rnl2tr + MBP = T4 RNA ligase 2 truncated attached to an N-terminal maltose binding protein tag. All mutations indicated are substitutions in T4 Rnl2tr + MBP. Data are shown as the mean +/- SEM of at least three independent experiments. * denotes difference in means p