Table 1.

Inhibition constants of phosphinate against GspS and various TryS enzymes. All assays were performed under conditions approximating to the intracellular physiological state (i.e. pH 7.2, 2 mm Spd, 0.2 mm GSH and 2 mm Mg²⁺-ATP), and were initiated with 100 nm each enzyme in the presence of various phosphinate concentrations. IC₅₀ values and slope factors are from the inhibition profiles determined from Eqn (7), and K_i^app values were determined from the tight-binding inhibition equation (Eqn 8). The errors represent the standard error of the fit to the appropriate equation.

	Enzyme
Inhibition constants	CfGspS	CfTryS	L. major TryS	T. cruzi TryS	T. brucei TryS
IC50 (nm)	72 ± 6	1380 ± 380	650 ± 25	530 ± 20	1300 ± 50
Slope factor	1.2 ± 0.1	1.1 ± 0.3	1.1 ± 0.04	1.1 ± 0.04	1.1 ± 0.05
Kiapp (nm)	29 ± 5	1330 ± 350	580 ± 30	490 ± 20	1200 ± 500