Defining the structural consequences of mechanism-based inactivation of mammalian cytochrome P450 2B4 using resonance Raman spectroscopy.
In view of the potent oxidizing strength of cytochrome P450 intermediates, it is not surprising that certain substrates can give rise to reactive species capable of attacking the heme or critical distal-pocket protein residues to irreversibly modify the enzyme in a process known as mechanism-based (MB) inactivation, a result that can have serious physiological consequences leading to adverse drug-drug interactions and toxicity. While methods exist to document the attachment of these substrate fragments, it is more difficult to gain insight into the structural basis for the altered functional properties of these modified enzymes. In response to this pressing need to better understand MB inhibition, we here report the first application of resonance Raman spectroscopy to study the inactivation of a truncated form of mammalian CYP2B4 by the acetylenic inhibitor 4-(tert-butyl)phenylacetylene, whose activated form is known to attach to the distal-pocket T302 residue of CYP2B4.
Mak
Piotr J
PJ
Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53233, USA.
Zhang
Haoming
H
Hollenberg
Paul F
PF
Kincaid
James R
JR
D000114:Acetylene / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D000072467:Cytochrome P450 Family 2; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman
C044736:phenylacetylene; D001189:Aryl Hydrocarbon Hydroxylases; D000072467:Cytochrome P450 Family 2; C465241:cytochrome P-450 CYP2B4 (rabbit); D000114:Acetylene