Cytochrome P450s (P450s) are subject to inhibition/inactivation by various chemically diverse agents, which may interact directly or indirectly with either the P450 prosthetic heme or the protein moiety or with both moieties. This inhibition is clinically relevant, as it can block physiological pathways as well as result in therapeutically significant beneficial or adverse effects and clinically relevant drug–drug interactions. Herein, we discuss the various chemical agents and their chemical mechanisms that lead to such reversible, quasi-irreversible, or irreversible inhibition of these enzymes. We note that such inhibition targeted at P450-dependent physiological and/or pathological processes has been ingeniously and effectively harnessed not only in the design and development of clinically relevant therapeutic agents but also of fungicides, insecticides, and herbicides.

Inhibition of Cytochrome P450 Enzymes

One stop mycology

The biosynthesis of steroids and triterpenoids

Bioactive small molecules reveal antagonism between the integrated stress response and sterol-regulated gene expression

The amino acid residues affecting the function of rat sterol 14-demethylase P450 (CYP51) were examined by means of point mutation. Forty-five mutants with respect to 27 amino acid sites were constructed and expressed in Escherichia coli. Substitution of highly conserved Y131, E369, R372, or R382 decreased the expression of CYP51 protein, indicating some structural importance of these residues. Substitution of H314, T315, or S316 caused considerable effects on the catalytic activity, and T315 was identified as the "conserved threonine" of CYP51. H314 was important for maintenance of the activity of CYP51 and was a characteristic residue of this P450, because the position corresponding to this residue is occupied by an acidic amino acid in most other P450 species. A144 was identified as a residue affecting the interaction of CYP51 with ketoconazole. Substitution of A144 with I, which occupies the corresponding position in fungal CYP51, enhanced the ketoconazole susceptibility of rat CYP51 with little change in the catalytic activity, indicating an important role of this residue in determination of the ketoconazole susceptibility of CYP51. Alteration of the catalytic activity was caused by the substitution at some other sites, whereas substitution of a few highly conserved amino acids caused little alteration of the activity of CYP51.

https://www.jstage.jst.go.jp/article/biochemistry1922/129/5/129_5_761/_pdf

The amino acid residues affecting the activity and azole susceptibility of rat CYP51 (sterol 14-demethylase P450).

Selectivity of isoprenoid-containing imidazole antifungal compounds for sterol 14-demethylase P450 (P45014dm) and 7-ethoxycoumarin O-deethylase P450 of rat liver microsomes

Ito Tamami

Papers

Selectivity of isoprenoid-containing imidazole antifungal compounds for sterol 14-demethylase P450 (P45014dm) and 7-ethoxycoumarin O-deethylase P450 of rat liver microsomes