. Author manuscript; available in PMC: 2013 Nov 14.

Published in final edited form as: Biochemistry. 2011 Nov 22;50(50):10.1021/bi200924t. doi: 10.1021/bi200924t

Table 1.

Paramagnetic relaxation rates (R_P) and calculated (r_app and r_min) of MDZ or CBZ bound to CYP3A4.

Peak	R_Fe3+ (sec⁻¹)	R_Fe2+-CO (sec⁻¹)	R_P (sec⁻¹)	r_ap_p^a (Å)	r_min (Å)
260 μM Midazolam
1′	2.18±0.02	1.53±0.04	0.65±0.05	9.15±0.22	7.62±0.18^b
3	1.88±0.04	1.45±0.18	0.43±0.18	9.79±0.71
7	1.81±0.05	1.67±0.09	0.14±0.10	11.83±1.50
9	2.97±0.17	1.65±0.12	1.31±0.20	8.14±0.27
10	2.85±0.06	1.81±0.11	1.03±0.12	8.47±0.24
3F	1.60±0.07	1.46±0.20	0.14±0.21	11.84±2.95
4F	1.85±0.04	1.91±0.07	−0.06±0.08	-	17.02^c
5F	2.17±0.06	1.72±0.10	0.45±0.11	9.75±0.46
6F	1.88±0.05	1.83±0.11	0.05±0.12	14.13±6.01

260 μM Carbamazepine
aa′	2.44±0.24	1.67±0.11	0.77±0.26	7.88±0.45	7.02±0.40^b
bb′	2.56±0.33	1.54±0.09	1.03±0.34	7.51±0.42	6.69±0.38^b
cc′	2.38±0.23	1.59±0.10	0.79±0.25	7.84±0.41	6.98±0.37^b
dd′	2.50±0.25	1.47±0.09	1.03±0.26	7.51±0.33	6.69±0.29^b
ee′	2.22±0.20	1.52±0.09	0.71±0.22	7.99±0.41	7.12±0.37^b

r_app was calculated using eq 6.

r_min was calculated based on chemical equivalence (eq 7).

r_min was calculated using the highest R_P.

Abbreviations: R_Fe3+, paramagnetic relaxation rate (sec⁻¹) of oxidized CYP3A4; R_Fe2+-CO, paramagnetic relaxation rate (sec⁻¹) of reduced CYP3A4 with CO; R_P, paramagnetic relaxation rate (i.e. R_P=R_Fe3+−R_Fe2+-CO). The distances were calculated with a τ_C of 3 × 10⁻¹⁰ sec, which is the average value of P450s under variety of conditions (31, 49). The NMR relaxation rates of 4a and 4b protons were omitted because of overlap of their NMR peaks with water and aliphatic proton NMR peaks.