Table 2.

Kinetics of UB activation by wtUba1 and Uba1 mutants measured by ATP-PPi exchange assay.

	K1/2 (µM)	kcat (min−1)	kcat/K1/2 (µM−1 min−1)		K1/2 (µM)	kcat (min−1)	kcat/K1/2 (µM−1 min−1)
UB1 – wtUba1	8.2 ± 0.2	15 ± 3	1.9	UB1 – Uab1-A1	2.0 ± 0.4	38 ± 7	19
UB8 – wtUba1	–	–	0.075	UB8 – Uba1-A5	1.4 ± 0.3	31 ± 2	22
Cross reactivity of UB10 – Uba1-A5 with wtUB-wtUba1 pair
UB10 – wtUba1	–	–	0.012	UB10 – Uba1-A5	4.4 ± 0.5	70 ± 9	16
wtUB – wtUba1	1.4 ± 0.1	50 ± 5	35	wtUB – Uba1-A5	–	–	0.011