TABLE 3.

tRNA discrimination by SepCysS

	Percentage conversion to Cys-tRNACys	Kd	kcat/Kma
	%	μm	min–1 μm–1
	52.2 ± 9.5	1.1 ± 0.2	0.009 ± 0.002
	75.3 ± 4.5	0.4 ± 0.15	0.014 ± 0.003
	72.2 ± 5.0	0.55 ± 0.18	0.012 ± 0.002
tRNACysΔ2	72.0 ± 8.0	NDb	ND
tRNACysΔ4	50.0 ± 6.0	ND	ND

^ak_cat/K_m values were determined from initial velocities using the relation ν = k_cat/K_m [E][S]

^bND, not determined