Table 1.

Rate constants for tRNA-independent AARS pre-transfer editing activities of standard amino acids^a

	Enzyme-dependent AMP formation (min−1)	Non-enzymatic hydrolysis of AA-AMP (min−1)	Fold difference	Ref
LeuRS Met	2.0	0.100	20	This work
IleRS Val	3.2	0.120	30	23
GlnRS-bGln	1.5	0.042	35	24
ProRS Ala	27.2	0.113	240	22,25
ValRS Thr	22.2	0.070	300	23

^aFor enzymatic AMP formation, k_obs was reported for all systems, except IleRS and ValRS activation of valine and threonine respectively, for which k_cat was reported. For non-enzymatic solution hydrolysis, k_obs was reported.

^bThe GlnRS-Gln system requires presence of tRNA^Gln.