TABLE 3.

Enzymatic rates of catalysis for Ufm1 activation by wild-type Uba5

The k_obs values for Ufm1-AMP, Uba5-S∼UBL, and Ufc1-S∼Ufm1 formation were determined by plotting quantified signal versus time and fitting to the single-exponential rise equation, Y = Ao × (1 − exp(−k_obs × t)).

Uba5 Reaction	Ufm1-AMPa	Uba5∼Ufm1	Ufc1∼Ufm1
	s−1	s−1	s−1
Ufm1	0.015 ± 0.002	0.021 ± 0.003	0.12 ± 0.012

^a The rates of Ufm1-AMP formation were performed at concentrations of ATP below K½ due to limitations of the TLC AMP release assay.