Table 1.

ATPase activity of spin-labeled NtrC derivatives^*

NtrC derivative	Concentration at 1 μM		Concentration at 5 μM
	Without phosphorylation	With phosphorylation†	Without phosphorylation	With phosphorylation†
Wild type	—	—	4	2,525
NtrC (minus cysteines)	—	—	21	2,195
NtrCD86C	1	699	27	2,115
NtrCD86C*	1	580	4	2,023
NtrCD86C, S160F	908	1,813	—	—
NtrCD86C*, S160F	181	1,896	—	—

^*ATPase activity (pmol/10 μl per 10 min) was measured at 37°C. 

^†NtrC proteins were phosphorylated with 10 mM carbamoyl phosphate and 8 mM MgCl₂ for 10 min at room temperature before the addition of ATP.