# Toxicological importance of CYP3A4 catalysis and inhibition

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2022 · $561,595

## Abstract

Program Director/Principal Investigator (Sevrioukova, Irina F.):
Project Summary
Human cytochrome P450 3A4 (CYP3A4) is the major and most clinically relevant drug-metabolizing enzyme,
notoriously known for its extreme substrate promiscuity and allosteric behavior. Drugs and other xenobiotics
can also stimulate and inhibit CYP3A4 activity, which frequently leads to undesired drug-drug interactions
(DDIs), chemical toxicity and therapeutic failures. Despite extensive investigations, the CYP3A4 inhibitory and
activation mechanisms remain incompletely understood. This proposal centers on using structural biology
approaches to address key issues in both areas of CYP3A4 research. Aim 1 is set to investigate the CYP3A4
inhibitory mechanism via rational structure-based design of analogues of ritonavir, an HIV protease inhibitor
whose ability to potently inhibit CYP3A4 was purely coincidental. We will identify structural determinants
required for potent inhibition by rationally designing and investigating structure-activity relations of ritonavir-like
compounds and, based on our findings, build a 3D-pharmacophore model for a potent CYP3A4-specific
inhibitor that can be used for early prediction/elimination of the inhibitory potential in drug candidates and for
development of more effective pharmacoenhancers. Aim 2 will utilize an integrated biochemical, chemical
labeling, structural and computational approach to investigate the CYP3A4 substrate binding cooperativity and
allosterism. Our recent structural findings confirmed the importance of the previously mapped peripheral area
and identified three novel inner sites that could serve for substrate/effector docking. We will evaluate the role
and relative importance of these areas by assessing how their modification/disruption affects CYP3A4
conformation, substrate binding cooperativity, stoichiometry and metabolism. The research outlined in this
proposal is important from both the basic and translational science perspectives, because it will fill the
knowledge gaps and provide fundamental insights into plasticity and adaptability of CYP3A4 to structurally
diverse ligands, clarify molecular mechanisms underlying the complex ligand binding behavior and oxidative
kinetics, and help develop better tools for in silico prediction of protein-ligand contacts, metabolic stability and
DDI potential in drug candidates to improve their efficacy and reduce off-target effects.
OMB No. 0925-0001/0002 (Rev. 08/12 Approved Through 8/31/2015) Page Continuation Format Page

## Key facts

- **NIH application ID:** 10358992
- **Project number:** 2R01ES025767-06A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Irina F Sevrioukova
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $561,595
- **Award type:** 2
- **Project period:** 2016-06-01 → 2026-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10358992

## Citation

> US National Institutes of Health, RePORTER application 10358992, Toxicological importance of CYP3A4 catalysis and inhibition (2R01ES025767-06A1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10358992. Licensed CC0.

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