Table 1.

Summary of kinetic inactivation constants for acetylenic mechanism-based inhibitors of P450s.

MBIa	CYPsb	KI (μM)	kinact (min-1)	kinact/KI (min-1μM-1)	Modified Sitec	Ref.
2EN	2B1	0.08	0.83	10.4	Protein	[28]
9EPh	2B1	0.14	0.45	3.2	Protein	[31]
5-P1P	2B1	100	0.92	0.0092	Heme	[33]
	2E1	50	1.31	0.026	Heme	[33]
	Δ2E1	54	0.78	0.014	Heme	[33]
4-P1B	2E1 (LM)	ND	0.21		ND	[33]
	2E1	ND	0.55		ND	[33]
2-P3B2	2E1 (LM)	ND	0.04		ND	[33]
	2E1	ND	0.13		ND	[33]
1-P2P1	2E1 (LM)	ND	0.3		ND	[33]
	2E1 (LM)	ND	0.16		ND	[33]
17-EE	2B1	11	0.2	0.018	Protein	[36]
	2B6	0.8	0.03	0.038	Protein	[36]
	3A4	18	0.04	0.0022	Protein+Heme	[35]
tBA	2B4	75	0.23	0.0031	Heme	[42]
	2E1	1000	0.2	2×10-4	Protein+Heme	[41]
tBMP	2E1	100	0.12	1.2×10-4	Heme	[41]
	2B1	17	0.56	0.33	Heme	[44]
tBPA	2B4	0.44	0.12	0.27	Protein	[45]
	2B1	0.7	1.64	2.3	Protein	[44]
	2B6	2.8	0.7	0.25	Protein+Heme	unpublished data
DMPB	2B6 (LM)	5.1	0.09	0.018	Heme	[54]

^aAbbreviations: 2EN, 2-ethynylnaphthalene; 9-EPh, 9-ethynylphenanthrene; 5-P1P, 5-phenyl-1-pentyne; 17EE, 17α-ethynylestradiol; tBA, tert-butyl acetylene; tBMP, tert-butyl-1-methyl-2-propynyl ether; tBPA, tert-butylphenylacetylene; 4-P1B, 4-phenyl-1-butyne; 2-P3B2, 2-phenyl-3-buty-2-ol; 1-P2P1, 1-phenyl-2-propyn-1-ol; DMPB, N-(3,5-Dichloro-4-pyridyl)-4-methoxy-3-(prop-2-ynyloxy)benzamide. The chemical structures of the listed MBIs are included in Table 1S in the Supplemental Materials.

^bLM, liver microsomes

^cND, not determined.