Table 2 KM values of WT and mutant AtGCL enzymes for cysteine, ATP and glutamate

Enzyme assays were performed as described under Materials and methods section. Values for KM (mM) are expressed as a mean ± SD (n > 3). Statistical analysis by Welch's ANOVA indicates that GCL variants (WT and mutants) do not differ significantly in their affinity for substrates. [FCys(2, 7.32) = 0.65, PCys = 0.55; FGlu(2, 9.10) = 3.48, PGlu = 0.08; FATP(2, 7.02) = 2.87, PATP = 0.12].

KM values
CysteineGlutamateATP
AtGCL WT0.34 ± 0.126.64 ± 1.021.25 ± 0.18
Glu141/Glu4030.33 ± 0.267.56 ± 0.581.16 ± 0.04
Lys201/Lys4790.28 ± 0.048.33 ± 1.151.45 ± 0.30