Table 1.

Kinetic Data for PsUC, PsAH, GbAH, GbAH‐UC, CaUAL, and ScUAL

	ATP cleavagea			Allophanate hydrolysisb			Urea amidolyase activitya
	k cat (s−1)	K M, app urea (mM)	k cat/K M (s−1 M−1)	k cat (s−1)	$K_{\mathrm{M}}^{\text{allo}}$ (mM)	k cat/K M (s−1 M−1)	k cat (s−1)	K M, app urea (mM)	k cat/K M (s−1 M−1)
PsUC	12 ± 1c	17 ± 3	(7.0 ± 1.0) × 102 d
PsAH				12 ± 1	0.22 ± 0.01	(5.3 ± 0.3) × 104
1:1 molar ratio PsUC:PsAH	11 ± 1	12 ± 1	(9.2 ± 1.1) × 102	11 ± 1	0.15 ± 0.01	(7.3 ± 0.8) × 104	1.2 ± 0.1	2.5 ± 0.5	(4.7 ± 1.0) × 102
GbAH				18 ± 1	0.10 ± 0.01	(1.8 ± 0.1) × 105
GbAH‐UC	29 ± 1	1.8 ± 0.2	(1.6 ± 0.2) × 104	15 ± 1	0.21 ± 0.01	(6.8 ± 0.4) × 104	2.7 ± 0.1	1.7 ± 0.1	(1.6 ± 0.1) × 103
ScUAL	22 ± 1	0.7 ± 0.1	(3.0 ± 0.3) × 104	32 ± 1	0.23 ± 0.03	(1.4 ± 0.2) × 105	2.6 ± 0.1	0.3 ± 0.1	(9.2 ± 3.4) × 103
CaUAL	11 ± 1	0.6 ± 0.1	(1.8 ± 0.3) × 104	24 ± 1	0.23 ± 0.01	(1.0 ± 0.1) × 105	0.80 ± 0.03	0.2 ± 0.1	(3.6 ± 0.7) × 103

^a50 mM HEPES (pH 7.3), 50 mM NaCl, 8 mM MgSO₄, 8 mM NaHCO₃, 0.5‐50 mM Urea, 100 µM ATP.

^b50 mM HEPES (pH 7.3), 50 mM NaCl, 0.1–10 mM allophanate.

^cReported errors represent the standard error from the nonlinear regression fit to the Michaelis–Menten equation. The curves were fit to the average of three independent velocity measurements at five different substrate concentrations.

^dReported errors are propagated from the K _M and k _cat measurements in the preceding column.