Fig 5.

Physicochemical properties of recombinant aKMT protein. (A) Effect of temperature on the methyltransferase activity of aKMT. aKMT was incubated with recombinant Cren7 for 10 min (■) or 90 min (▲) at the indicated temperatures in the presence of [³H]SAM. The samples were precipitated with TCA, and radioactivity in the pellets was counted in a liquid scintillation counter. The highest activity obtained in the 90-min assay was defined as 100%. (B) Thermostability of aKMT. aKMT was incubated for the indicated lengths of time at 80°C (■) or 90°C (▲). The methyltransferase activity of the enzyme was then measured with recombinant Cren7 as the substrate at 50°C. (C) Effect of NaCl concentration on the methyltransferase activity of aKMT. aKMT was incubated with recombinant Cren7 and [³H]SAM for 90 min at 50°C in the presence of NaCl at the indicated concentrations. The samples were treated as described above for liquid scintillation counting. All numbers are the averages of three independent measurements.