TABLE 2.

Steady-state parameters for UCK-1^a

Substrate	Km (μM)	kcat (s−1)	kcat/Km (μM−1 s−1)
Cytidine	131 ± 27	0.50 ± 0.04	3.8 × 10−3
Uridine	407 ± 52	0.51 ± 0.03	1.3 × 10−3
2′-Deoxycytidine	NA, 1 mMb	NA, 1 mM	NA, 1 mM
2′-C-Me-C	NA, 3 mMc	NA, 3 mM	NA, 3 mM
PSI-6130	NA, 3 mM	NA, 3 mM	NA, 3 mM

^aValues are reported as means ± standard deviations.

^bNA, 1 mM, no activity was observed up to 1 mM.

^cNA, 3 mM, no activity was observed up to 3 mM.