FIGURE 3.

Mimivirus Tgs catalyzes a single methyl addition at cap guanine-N2 and has relaxed cap specificity at alkaline pH. Reaction mixtures (10 μL) containing either 50 mM Tris-HCl (pH 8.0) or 50 mM Tris-acetate (pH 6.0) as indicated; 5 mM DTT, 50 mM NaCl, 100 μM [³H-CH₃]AdoMet, 1 mM methyl acceptor as specified; and 1 μg (A,B) or 0.5 μg (C) of MimiTgs were incubated for 60 min at 37°C. Aliquots (6 μL) were spotted on PEI-cellulose TLC plates, which were developed with 0.2 M (NH₄)₂SO₄ (A) or 0.05 M (NH₄)₂SO₄ (B,C). ³H-labeled material was visualized by autoradiography.