. Author manuscript; available in PMC: 2010 Jul 28.

Published in final edited form as: Biochemistry. 2009 Jul 28;48(29):7045–7055. doi: 10.1021/bi9005072

Table 1.

Comparison of kinetic parameters of B. anthracis glutamate racemase, RacE2 (RacE2_WT), and its mutants. Kinetics was determined using two different assay methods as described in materials and methods. Freshly purified enzyme was used for each assay. The kinetic measurements were repeated at least twice (and in some cases three times) with different batches of protein preparations and were found to vary by about two fold with different batches. Representative measurements from one batch (done in triplicate) are shown here.

The quaternary structure (determined by gel filtration) for each mutant is listed as either a monomer (M), dimer (D) or as a monomer-dimer equilibrium (M ↔ D).

	LGlu → DGlu			DGlu → LGlu			Quaternary structure +/−DGlu
	K_m (mM)	k_cat (min⁻¹)	k_cat/K_m (M⁻¹s⁻¹)×10³	K_m (mM)	k_cat (min⁻¹)	k_cat/K_m (M⁻¹s⁻¹)×10³	Quaternary structure +/−DGlu
RacE2_WT	6.1 ± 0.8	1944 ± 84	5.3 ± 0.7	0.07 ± 0.01	13 ± 0	3.1 ± 0.4	D
R25A	5.8 ± 0.4	4900 ± 112	14.1 ± 1.0	0.14 ± 0.03	126 ± 7	15 ± 3.3	M
R214A/K106A	11.0 ± 0.9	4640 ± 140	7.0 ± 0.6	0.16 ± 0.03	133 ±12	13.9 ± 2.9	M
K29A	7.2 ± 1.0	5100 ± 244	11.8 ± 1.8	0.25 ± 0.03	124 ± 19	8.3 ± 1.6	M ↔ D
P99A	4.1 ± 0.3	2740 ± 60	11.1 ± 3.5	0.17 ± 0.02	128 ± 10	12.5 ± 1.8	M ↔ D
K106A	10.8 ± 1.4	3660 ± 200	5.6 ± 0.8	0.42 ± 0.03	87 ± 0	3.5 ± 0.2	M ↔ D
R214A	10.1 ± 0.9	5920 ± 200	9.8 ± 0.9	0.30 ± 0.03	111 ± 14	6.2 ± 1.0	M ↔ D
Q86A	8.8 ± 1.8	2400 ± 180	4.5 ± 1.0	0.1 ± 0.01	36 ± 2	6.0 ± 0.7	D
Y221A	9.9 ± 1.2	4200 ± 200	7.1 ± 0.9	0.13 ± 0.01	46 ± 2	5.9 ± 0.5	D