Table 1.
Kinetic parameters for the NADPH-dependent reduction of steroid hormones by purified recombinant murine AKR isoforms.
| Enzyme |
Km (μM) |
kcat (min-1) |
kcat/Km (min-1.mM-1) |
Enzyme |
Km (μM) |
kcat (min-1) |
kcat/Km (min-1.mM-1) |
|---|---|---|---|---|---|---|---|
| Adione | Estrone | ||||||
| AKR1C1 | 35.9 ± 4.4 | 5.24 ± 0.36 | 146 | AKR1C1 | na | na | na |
| AKR1C2 | 1.9 ± 0.7 | 1.51 ± 0.10 | 795 | AKR1C2 | na | na | na |
| AKR1C3 | 3.8 ± 1.0 | 0.79 ± 0.05 | 210 | AKR1C3 | na | na | na |
| AKR1C4 | 7.4 ± 2.1 | 4.64 ± 0.39 | 627 | AKR1C4 | na | na | na |
| AKR1C6 | 19.1 ± 4.5 | 10.33 ± 1.06 | 541 | AKR1C6 | 11.4 ± 3.5 | 5.15 ± 0.58 | 452 |
| AKR1C12 | na | na | na | AKR1C12 | na | na | na |
| AKR1C13 | na | na | na | AKR1C13 | na | na | na |
| AKR1C14 | na | na | na | AKR1C14 | na | na | na |
| AKR1C18 | na | na | na | AKR1C18 | 8.9 ± 4.4 | 5.8 ± 0.95 | 652 |
| AKR1C19 | na | na | na | AKR1C19 | na | na | na |
| AKR1C20 | na | na | na | AKR1C20 | na | na | na |
| AKR1C21 | nmm | nmm | nmm | AKR1C21 | na | na | na |
| Progesterone | 5α-DHT | ||||||
| AKR1C1 | 4.2 ± 1.0 | 1.77 ± 0.13 | 421 | AKR1C1 | 46.9 ± 6.5 | 6.85 ± 0.45 | 146 |
| AKR1C2 | na | na | na | AKR1C2 | 4.3 ± 0.6 | 2.03 ± 0.08 | 472 |
| AKR1C3 | 0.9 ± 0.3 | 0.14 ± 0.01 | 156 | AKR1C3 | na | na | na |
| AKR1C4 | 9.4 ± 3.5 | 0.74 ± 0.09 | 79 | AKR1C4 | 6.7 ± 1.9 | 7.34 ± 0.66 | 1096 |
| AKR1C6 | 25.1 ± 5.6 | 4.81 ± 0.87 | 192 | AKR1C6 | 5.8 ± 2.2 | 0.93 ± 0.10 | 160 |
| AKR1C12 | na | na | na | AKR1C12 | na | na | na |
| AKR1C13 | na | na | na | AKR1C13 | na | na | na |
| AKR1C14 | na | na | na | AKR1C14 | na | na | na |
| AKR1C18 | 105.7 ± 29.1 | 114.12 ± 19.2 | 1080 | AKR1C18 | 3.9 ± 0.5 | 22.41 ± 0.82 | 5746 |
| AKR1C19 | na | na | na | AKR1C19 | na | na | na |
| AKR1C20 | 3.7 ± 1.2 | 0.51 ± 0.05 | 138 | AKR1C20 | na | na | na |
| AKR1C21 | na | na | na | AKR1C21 | nnm | nnm | nnm |
adione, androstanedione
5α-DHT, 5α-dihydrotestosterone
na, no detectable activity
nmm, data does not fit a Michaelis-Menten curve