. 2018 Jul 2;115(29):7527–7532. doi: 10.1073/pnas.1807109115

Table 2.

Kinetics of aminoacylation by human AlaRS mutants

Human AlaRS	k_cat, s⁻¹	K_m, μM	k_cat/K_m, μM⁻¹⋅s⁻¹	Rel k_cat/K_m
WT	0.23 ± 0.01	0.26 ± 0.04	0.89 ± 0.18	1
N317A	0.20 ± 0.01	0.29 ± 0.05	0.69 ± 0.15	0.78
N317D	0.024 ± 0.001	0.41 ± 0.11	0.058 ± 0.018	0.065
D416A	0.32 ± 0.02	0.35 ± 0.08	0.92 ± 0.26	1.0
D416N	0.20 ± 0.01	0.47 ± 0.07	0.43 ± 0.08	0.48
N317A/D416A	0.21 ± 0.01	0.23 ± 0.06	0.90 ± 0.31	1.0

Assays were carried out at 25 °C and pH 7.5, with tRNA^Ala concentrations ranging from 62.5 nM to 24.7 μM. Enzyme concentrations were 20 nM (WT), 43 nM (N317A), 250 nM (N317D), 50 nM (D416A), 50 nM (D416N), and 25 nM (N317A/D416A). The data represent the mean of triplicate experiments ± SEM.