Table 3.

Kinetic parameters for equilibrium binding of pyruvate and 2-oxobutanoate analogs to GCL variants.^a)

Substitutions in GCL	Kd (S0.5) AcPhi (mM)	Kd (S0.5), PrPhi (mM)	Kd, MAP (mM)
I393A	0.32 ± 0.02 (nH = 2.23)	0.46 ± 0.03 (nH = 1.7)	1.4 ± 0.09
V51D	0.18 ± 0.11b)	-	0.11 ± 0.09b)
V51D/I393A	0.37 ± 0.09 (nH = 1.29)	0.28 ± 0.04 (nH = 1.1)	0.11 ± 0.1

^a)Kinetic parameters were determined in steady state CD experiments.

^b)For V51D GCL no 1′,4′-iminopyrimidine tautomers from addition of AcPhi and MAP were detected. Instead, the intensity of the CD₃₀₂ band was reduced by AcPhi and MAP with values of S_0.5 presented in Table.