Table 1.

Estimates of K_m and k_obs for Uba6~Ubl thioester formation assays

Uba6~Ub thioester reaction	Km (μM)	Vmax (nM s−1)	kobs (s−1)	kobs/Km (μM−1 s−1)
Uba6_Apo	0.77 ± 0.063	29.2 ± 0.652	0.63 ± 0.043	0.82
Uba6_Apo + 50 μM InsP6	0.66 ± 0.030	12.0 ± 0.144	0.16 ± 0.021	0.24
Uba6_WT	0.71 ± 0.118	10.6 ± 0.471	0.19 ± 0.008	0.27
Uba6~FAT10 thioester reaction
Uba6_Apo	0.34 ± 0.028	35.0 ± 0.624	0.47 ± 0.036	1.4
Uba6_Apo + 50 μM InsP6	0.27 ± 0.039	7.39 ± 0.217	0.13 ± 0.010	0.48
Uba6_WT	0.28 ± 0.038	3.83 ± 0.106	0.14 ± 0.009	0.5

The values for Uba6~Ubl formation were determined by plotting quantified signal versus time and fitting to the single exponential rise equation, Y = A₀ × (1 − exp(−k_obs × t)).