Table 2.

Thermal stability for 44OOC-5 wild type and the E179Q mutant in the presence of nucleotide under different redox conditions

Nucleotidea	44OOC-5		44OOC-5E179Q
	Oxidizedb	Reducedc	Oxidizedb	Reducedc
None	45.2 ± 0.3	42.0 ± 0.2	44.7 ± 0.2	41.7 ± 0.2
AMP	44.7 ± 0.7	—	44.9	—
ADP	53.5 ± 0.4	50.7 ± 0.6	52.4 ± 0.7	50.4 ± 0.1
ATP	50.2 ± 0.4	46.1 ± 0.2	52.1 ± 0.5	48.1 ± 0.2
ATPγS	50.4 ± 0.7	46.8	52.1	—
AMPPNP	45.7	—	—	—
AMPPCP	44.9	—	—	—

Thermal stability, Tm (°C), was measured as a midpoint of the transition temperature by monitoring far UV-CD ellipticity at 222 nm. The data shown here are the mean value ± SE calculated from at least three different experiments setting from two different purification preps, except the measured value only from single experiment.

^a Nucleotide without Mg²⁺ was added to protein solution under oxidized or reduced conditions to 500 μM concentration before measurement.

^b Wild type or E179Q 44OOC-5 was 5 μM monomer concentration in 20 mM phosphate buffer, 200 mM NaCl, pH 8.5, in the absence of reductant (oxidized).

^c Reduced protein was incubated in 0.5 mM TCEP for 30 min at 20°C before measurement.