Table 1. Association (kon) and dissociation (koff) rate constants and equilibrium dissociation constant (Kd) characterizing complex formation of cytochromes P450 with their redox partners in the absence/presence of the NADPH cofactor.
|
Protein complex |
NADPH |
kon, M-1s-1 |
koff, s-1 |
Kd, µM |
|
CYP3A4/CYB5A |
- |
(6.6±0.2)•103* |
(2.0±0.1)•10-3 |
0.30±0.03 |
|
CYP3A4/CYB5A |
+ |
(6.8±0.3)•103 ↔ ** |
(1.9±0.1)•10-3 ↔ |
0.27±0.03 ↔ |
|
CYP2E1/CYB5A |
- |
(6.3±0.3)•103 |
(2.7±0.2)•10-3 |
0.44±0.04 |
|
CYP2E1/CYB5A |
+ |
(6.6±0.2)•103 ↔ |
(2.6±0.2)•10-3 ↔ |
0.39±0.02 ↔ |
|
CYP3A4/CPR |
- |
(0.8±0.1)•103 |
(1.1±0.1)•10-3 |
1.37±0.12 |
|
CYP3A4/CPR |
+ |
(1.5±0.2)•103 ↑ |
(1.2±0.1)•10-3 ↔ |
0.80±0.05 ↓ |
|
CYP2E1/CPR |
- |
(7.4±0.5)•103 |
(3.6±0.2)•10-3 |
0.50±0.06 |
|
CYP2E1/CPR |
+ |
(8.6±0.4)•103 ↔ |
(3.8±0.2)•10-4 ↓ |
0.04±0.00 ↓ |
Note. * Data represent mean ± SD (n = 3). ** Asterisks show direction of changes of parameters of complex in the presence of NADPH versus control; (↔) – lack of significant changes of the analyzed parameter.