Table 2.

Comparison of thermodynamic properties for the oxidation reactions of mefenamic acid and testosterone catalyzed by cytochrome P450 BM3 M11 and recombinant human CYP1A2, as determined using our modified Arrhenius approach [Eq. (5)], the Curtin–Hammett principle [Eq. (6)], or SMARTCyp (to calculate differences in activation energies, ΔE _a).

Comparison for	Enzyme	ln (V max,1/V max,2) vs. 1000/T			Modified	Curtin–Hammett	SMARTCyp
the formation of:		Intercept	Slope [K]	R 2	Arrhenius: Δ	ΔΔG overall	ΔE a
					[kJ mol−1]	[kJ mol−1]	[kJ mol−1][a]
Mefenamic acid
3′‐OH‐MF vs. 4′‐OH‐MF	BM3 M11	3.0±0.2	−0.97±0.05	0.97	8.1±0.5	0.7	−1.8
3′‐OH‐MF vs. 5‐OH‐MF	BM3 M11	5.3±0.2	−0.97±0.07	0.98	8.1±0.6	−4.9	−1.8
4′‐OH‐MF vs. 5‐OH‐MF	BM3 M11	2.3±0.2	0.00±0.07	0.14	0.0±0.6	−5.6	0
4′‐OH‐MF vs. 5‐OH‐MF	CYP1A2	2.8±0.3	−0.74±0.10	0.97	6.1±0.8	−0.8	0
Testosterone
15β‐OH‐T vs. 16β‐OH‐T	BM3 M11	7.6±0.5	−1.95±0.14	0.99	16.7±1.1	−2.8	0
2β‐OH‐T vs. 16β‐OH‐T	BM3 M11	9.1±0.5	−2.82±0.16	0.99	23.5±1.3	0.8	−9.5
2β‐OH‐T vs. 15β‐OH‐T	BM3 M11	1.4±1.0	−0.87±0.29	0.82	7.2±2.5	3.6	−9.5

[a] SMARTCyp activation energies: 3′‐OH‐MF, 66.4 kJ mol⁻¹; 4′‐OH‐MF, 68.2 kJ mol⁻¹; 5‐OH‐MF, 68.2 kJ mol⁻¹; 2β ‐OH‐T, 66.4 kJ mol⁻¹; 15β ‐OH‐T, 75.9 kJ mol⁻¹; 16β ‐OH‐T, 75.9 kJ mol⁻¹.