TABLE 2.

Thermodynamic parameters of nucleotide binding to AtAPSK

All titrations were performed at 17 °C with resulting data fit to a two-site binding model as described under “Experimental Procedures.”

Ligand	K1	K2	ΔH1	ΔH2
	μm		kcal mol−1
ATP	1.25 ± 0.09	24.7 ± 6.9	−6.4 ± 0.7	−5.0 ± 0.7
ATPγS	0.26 ± 0.05	7.9 ± 0.1	−12.2 ± 0.4	−5.2 ± 0.3
AMP-PNP	19.6 ± 1.5	361 ± 45	−4.8 ± 0.5	−1.2 ± 0.6
AMP-PNP + 5 mm Mg2+	16.4 ± 0.2	82.6 ± 7.7	−6.0 ± 0.1	−3.3 ± 0.4
ADP	0.18 ± 0.05	4.8 ± 0.6	−16.5 ± 0.2	−9.4 ± 0.1
ADP + 5 mm Mg2+	1.8 ± 0.4	38.1 ± 4.2	−10.7 ± 0.8	−6.2 ± 1.6
APS	66.7 ± 10.5	325 ± 89	−5.6 ± 0.9	−1.9 ± 0.7
APS + 5 mm Mg2+	80.4 ± 5.2	460 ± 99	−5.1 ± 2.3	−2.2 ± 0.8