Effect of pH and temperature on AtCinA activity.

<p>A) pH profile for AtCinA. The assay conditions at 37°C were 0.5 mM NMN and 14 nM purified AtCinA. The buffers used (50 mM) were sodium phosphate (pH 6.0–7.5), Tris-HCl (pH 8.0) and glycine-NaOH (pH 9.0–10.0). Sodium acetate at pH 5.0 was used at 160 mM in order to maintain the same ionic strength. B) pH-stability. AtCinA was incubated at 37°C for different periods of time at different pHs, and the activity was measured under standard conditions. The buffers used (50 mM) were sodium phosphate pH 6.0 (■), pH 7.0 (▲), pH 7.5 (▼), Tris-HCl pH 8.0 (○), glycine pH 9.0 (∕) and pH 10.0 (<b>△</b>), except for sodium acetate pH 5.0 (●), which was at 160 mM as in A). C) Temperature profile for AtCinA activity. Conditions were the same as above, but at different temperatures (20–90°C) in 50 mM sodium phosphate pH 7.5. D) Thermal stability at pH 7.5. AtCinA was incubated for different periods of time at different temperatures [4°C (●), 25°C (■), 35°C (▲), 40°C (▼), 50°C (○), 60°C (∕), and 70°C (ρ)], and the activity was measured in the standard reaction conditions.