TABLE 3.

Steady-state kinetic constants for divalent metal-activated OAH from C. parasitica-catalyzed hydrolysis of oxaloacetate and cleavage of (2R,3S)-dimethylmalate at 25 °C

Cofactor	Substrate	kcat	Km OAH	kcat/Km
		s−1	μm	m−1s−1
Mn2+	Oxalacetatea	35.2 ± 1.0	480 ± 7a	7.3 × 104
	(2R,3S)-Dimethylmalateb	(6.1 ± 0.1) ×10−3	147 ± 26	4.1 × 101
Mg2+	Oxalacetatec	3.6 ± 0.5	134 ± 19	2.7 × 104
	(2R,3S)-Dimethylmalateb	(1.6 ± 0.1) ×10−2	377 ± 50	4.2 × 101
Ca2+	Oxalacetated	1.9 ± 0.05	1248 ± 94	1.5 × 103
	(2R,3S)-Dimethylmalateb	Undetectable

^a Reaction solutions contained 0.2–5.0 mm oxalacetate, 5 mm Mn²⁺, and 0.15 μm OAH.

^b Reaction solutions contained 0.2–4.0 mm (2R,3S)-dimethylmalate, 5 mm metal²⁺, and 20 μm OAH.

^c Reaction solutions contained 0.1–2.0 mm oxalacetate, 5 mm Mg²⁺, and 0.3 μm OAH.

^d Reaction solutions contained 0.2–2.0 mm oxalacetate, 5 mm Ca²⁺, and 0.15 μm OAH.