Table 1.

Spectral changes in CYP11A1 elicited by inhibitors and activators^a

Drug	λmax in the absolute spectrum, nm	λmin and λmax in the difference spectrum, nm	ΔAmax in the difference spectrumb	Spectral Kdc
None	417	NAd	NA	NA
Inhibitors
Ketoconazole	422	412, 432	0.1 ± 0.01	1.5 ± 0.2
Posaconazole	422	411, 429	0.02 ± 0.001	1.0 ± 0.2
Carbenoxolone	417e	WSRf	<0.004	NDg
Selegeline	417e	NOh	NA	ND
Activators
Pemirolast	417e	NO	NA	ND
Clobenpropit	420	412, 433	0.03 ± 0.008	18.0 ± 2.0
Dexmedetomidine	421	413, 434	0.08 ± 0.01	7.0 ± 1.0
Desogestrel	417e	WSR	<0.002	ND
Tizanidine	417e	NO	NA	ND

^aThe assay buffer was 40 mM KP_i, pH, 7.2, containing 1 mM EDTA.

^bNormalized per nmol of CYP11A1, except cases with weak or no spectral response.

^cThe results are the mean ± S.D of three independent titrations.

^dNA, non applicable.

^eThe absorbance at λ_max was decreased by 2–8%.

^fWSR, weak spectral response.

^gND, not determined.

^hNO, not observed.