Table 1. Kinetic Parameters for ScOMPDC-Catalyzed Decarboxylation of OMP and FOMP^a.

	OMPb		FOMPc
ScOMPDC	kcat/Km (M–1 s–1)	ΔΔG⧧ (kcal/mol)d	kcat/Km (M–1 s–1)	ΔΔG⧧ (kcal/mol)d	e
wild-type	1.1 × 107		1.2 × 107		1.1
Q215A	2.6 × 105	2.2	2.0 × 106	1.1	7.7
Y217F	1.8 × 105	2.4	1.1 × 106	1.4	6.1
R235A	910	5.6	1.6 × 105	2.6	180
S154A	630	5.8	2.9 × 105	2.2	460
S154A/Q215A	380	6.1	7.7 × 104	3.0	200
S154A/Y217F	0.75 ± 0.01	9.8	520 ± 10	5.9	700
S154A/R235A	0.027 ± 0.004	11.7	20 ± 2	7.9	740
Q215A/Y217F	3.4 × 103	4.8	5.3 × 104	3.2	16
Q215A/R235A	14	8.0	7200	4.4	510
Y217F/R235A	4.1	8.8	820	5.7	200
S154A/Q215A/Y217F	0.28 ± 0.02	10.4	250 ± 10	6.4	890
S154A/Q215A/R235A	0.018 ± 0.001	12.0	10 ± 1	8.3	560
S154A/Y217F/R235A	0.0006 ± 0.0002f	14.0	0.44 ± 0.02	10.1
Q215A/Y217F/R235A	0.037	11.6	28	7.7	760
S154A/Q215A/Y217F/R235A	0.0016 ± 0.0005f	13.4	1.1 ± 0.1	9.6

^aConditions: pH 7.1 (10 mM MOPS), 25 °C and I = 0.105 (NaCl).

^bThe new values for this manuscript are in bold type. The other rate constants are from ref (11) or (15). The quoted uncertainty is the standard error from the least-squares fit of the kinetic data to the appropriate kinetic equation.

^cThe new values for this manuscript are in bold type. The other rate constants are from ref (10).The quoted uncertainty in the original values is the average of two or more determinations of k_cat/K_m.

^dCalculated from the ratio of the values of k_cat/K_m for wild-type and mutant ScOMPDC-catalyzed decarboxylation of OMP or FOMP.

^eThe ratio of the values of k_cat/K_m for OMPDC-catalyzed decarboxylation of OMP and FOMP.

^fNo detectable activity toward decarboxylation of OMP: k_cat/K_m < 0.006 M^–1 s^–1. The rate constants were estimated from k_cat/K_m for mutant enzyme-catalyzed decarboxylation of FOMP (see text). The range of values is calculated from the estimated uncertainty of ±50% in for OMPDC-catalyzed decarboxylation of OMP and FOMP.