Table 2.

Temperature dependence of the kinetic parameters for decarboxylation of OMP catalyzed by ScOMPDC, MtOMPDC and EcOMPDC at pH 7.1 and I = 0.1 (NaCl).^a

	ScOMPDC			MtOMPDC			EcOMPDC
Temp °C	kcatb s-1	kcat/Kmc M-1 s-1	Kmd μM	kcatb s-1	kcat/Kmc M-1 s-1	Kmd μM	kcatb s-1
5	3.1 ± 0.5	2.7 ± 0.2 × 106	1.1 ± 0.2	0.64 ± 0.03	6.0 ± 2.2 × 105	1.1 ± 0.4	2.5 ± 0.1
10	4.6 ± 0.6	3.2 ± 0.2 × 106	1.4 ± 0.2				3.7 ± 0.1
12	5.1 ± 0.5
15	6.9 ± 0.9	5.6 ± 0.4 × 106	1.2 ± 0.2	2.0 ± 0.3	1.4 ± 0.2 × 106	1.5 ± 0.3	6.4 ± 0.1
17	7.8 ± 0.8
25	15 ± 1	1.1 ± 0.1 × 107	1.4 ± 0.2	4.7 ± 0.3	3.1 ± 0.3 × 106	1.5 ± 0.2	13 ± 1
35	27 ± 1	1.7 ± 0.4 × 107	1.6 ± 0.4	11 ± 1	4.2 ± 0.9 × 106	2.8 ± 0.6	23 ± 1
45	45 ± 4	1.4 ± 0.2 × 107	3.3 ± 0.6	24 ± 2	5.0 ± 1.3 × 106	4.8 ± 1.4	35 ± 1
50	59 ± 6	7.5 ± 0.3 × 106	7.9 ± 0.9
55				44 ± 2	6.1 ± 0.9 × 106	7.3 ± 1.1

^aThe quoted errors in k_cat and k_cat/K_m are standard errors that were obtained from multiple experiments to determine these parameters.

^bDetermined from the initial velocity of decarboxylation of OMP when [OMP]_o ≥ 20K_m. The observed values of k_cat were independent of enzyme concentration in the range 11 – 42 nM for ScOMPDC, 76 - 152 nM for MtOMPDC and 30 – 230 nM for EcOMPDC (see text).

^cDetermined from the first-order rate constant for decarboxylation of OMP ([OMP]_o ≤ 40 μM) when [OMP]_t = 0.3 – 0.5K_m (see text).

^dCalculated from the values of k_cat and k_cat/K_m. The standard error was obtained by propagation of the standard errors in k_cat and k_cat/K_m.