Figure 8.

Resistance of the WT P.abyssi TrmI enzyme and of the C196S+C233S mutant to thermodenaturation. The WT (open circles) and mutant (open squares) enzymes (400 µg/ml) were heated for different periods of time at 80 (A) or 85°C (B) in Tris–HCl 50 mM, MgCl₂ 10 mM. The remaining activity was measured at 70°C using total E.coli tRNA as substrate, [¹⁴C-methyl]AdoMet as methyl donor, and 10 µl of the preheated protein solution.