TABLE 2.
Steady-state kinetic parameters of 12α-HSDH homologs
| Homolog | Kinetic parameter | Substrate or coenzymea |
|||
|---|---|---|---|---|---|
| 12-Oxolithocholic acid | NADPH | Deoxycholic acid | NADP+ | ||
| rCSCI | Km (μM) | 17.52 ± 0.32 | 34.01 ± 0.32 | 178.61 ± 0.66 | 79.88 ± 0.37 |
| kcat (s−1) | 31.13 ± 1.56 | 26.71 ± 1.22 | 90.93 ± 4.46 | 90.74 ± 4.35 | |
| Vmax (μmol · min−1 · mg−1) | 66.15 ± 3.31 | 56.74 ± 2.59 | 193.19 ± 9.47 | 192.79 ± 9.24 | |
| kcat/Km (μM−1 · s−1) | 1.77 ± 0.109 | 0.79 ± 0.042 | 0.51 ± 0.029 | 1.14 ± 0.063 | |
| rCHYL | Km (μM) | 32.70 ± 0.55 | 48.31 ± 0.37 | 147.80 ± 0.38 | 110.53 ± 0.38 |
| kcat (s−1) | 45.09 ± 2.19 | 44.52 ± 2.30 | 72.52 ± 3.55 | 66.72 ± 3.18 | |
| Vmax (μmol · min−1 · mg−1) | 96.76 ± 4.70 | 95.53 ± 4.94 | 155.63 ± 7.64 | 143.18 ± 6.82 | |
| kcat/Km (μM−1 · s−1) | 1.38 ± 0.08 | 0.92 ± 0.056 | 0.49 ± 0.028 | 0.60 ± 0.033 | |
| rCHIR | Km (μM) | 34.29 ± 0.34 | 40.37 ± 0.38 | 175.44 ± 0.50 | 127.94 ± 0.42 |
| kcat (s−1) | 72.09 ± 3.50 | 76.24 ± 3.88 | 130.62 ± 7.88 | 129.75 ± 6.68 | |
| Vmax (μmol · min−1 · mg−1) | 151.82 ± 7.37 | 160.57 ± 8.16 | 275.08 ± 16.60 | 273.26 ± 14.07 | |
| kcat/Km (μM−1 · s−1) | 2.10 ± 0.12 | 1.89 ± 0.11 | 0.74 ± 0.052 | 1.01 ± 0.060 | |
a
The concentrations used in the assays were based on Km values (refer to Materials and Methods). Values represent the means ± SD based on three or more replications.