Table 1.
Kinetic parameters for the normal reaction, conversion of ICT to αKG, catalyzed by IDH1
Values result from fits of kinetic data using two different enzyme preparations. The standard error is determined from the deviance from these hyperbolic fits (Fig. 3, supplemental Fig. S3).
| IDH1 | Relative hydrophobicity of residue 132a | van der Waals volume of side chain at residue 132, Å3b | kcat (37 °C) | Km,ICT (37 °C) | Km,NADP+ (37 °C) | Efficiency, (kcat/Km, ICT, 37 °C) | kcat (21 °C) | Km,ICT (21 °C) | Km,NADP+ (21 °C) | Efficiency, mm−1 s−1 (kcat/Km, ICT, 21 °C) |
|---|---|---|---|---|---|---|---|---|---|---|
| s−1 | mm | mm−1 s−1 | s−1 | mm | mm−1 s−1 | |||||
| WT | −14 (R) | 148 (Arg) | 85 ± 4 | 0.22 ± 0.02 | 0.08 ± 0.03 | 3.9 ± 0.4 × 102 | 11.0 ± 0.4 | 0.015 ± 0.003 | 0.03 ± 0.01 | 7.3 ± 1.3 × 102 |
| H133Q | −14 (Arg) | 148 (Arg) | 45 ± 2 | 0.40 ± 0.08 | 0.16 ± 0.02 | 1.1 ± 0.2 × 102 | 9.4 ± 0.6 | 0.28 ± 0.07 | 0.101 ± 0.008 | 35 ± 9 |
| A134D | −14 (Arg) | 148 (Arg) | 2.3 ± 0.2 | 8 ± 2 | 1.2 ± 0.3 | 0.29 ± 0.08 | 0.200 ± 0.008 | 2.7 ± 0.3 | 0.7 ± 0.1 | 0.074 ± 0.003 |
| R100Q | −14 (Arg) | 148 (Arg) | 5.6 ± 0.4 | 8 ± 2 | 0.18 ± 0.02 | 0.7 ± 0.2 | 1.40 ± 0.06 | 9 ± 1 | 0.070 ± 0.006 | 0.16 ± 0.02 |
| R132H | 8 (His) | 118 (His) | 2.4 ± 0.1 | 4.2 ± 0.6 | 1.6 ± 0.5 | 0.57 ± 0.08 | 0.120 ± 0.006 | 6 ± 1 | 1.0 ± 0.9 | 0.020 ± 0.003 |
| R132C | 49 (Cys) | 86 (Cys) | 4.4 ± 0.1 | 8.2 ± 0.8 | 0.75 ± 0.07 | 0.54 ± 0.05 | 1.61 ± 0.08 | 5.3 ± 0.8 | 0.58 ± 0.08 | 0.30 ± 0.05 |
| R132G | 0 (Gly) | 48 (Gly) | 9.3 ± 0.6 | 7 ± 1 | 0.067 ± 0.007 | 1.3 ± 0.2 | 1.0 ± 0.06 | 3.6 ± 0.6 | 0.14 ± 0.02 | 0.28 ± 0.05 |