Exploring the structure characteristics and major channels of cytochrome P450 2A6, 2A13, and 2E1 with pilocarpine

Area of Science:

• Biochemistry
• Pharmacology
• Computational Chemistry

Background:

• Cytochromes P450 (CYP) are vital for metabolizing endogenous and exogenous compounds.
• Some CYP metabolic products are carcinogenic, making CYP inhibition a strategy for detoxification.
• Understanding CYP isoform-specific interactions is key for developing targeted inhibitors.

Purpose of the Study:

• To investigate the structural and dynamic differences in three P450 isoforms (CYP2A6, CYP2A13, CYP2E1) when bound to pilocarpine.
• To elucidate the molecular mechanisms underlying differential channel selection and inhibitor binding in these isoforms.
• To provide insights into structure-function relationships for developing effective CYP inhibitors.

Main Methods:

• Molecular Dynamics (MD) simulations.
• Adaptive Steered Molecular Dynamics (ASMD) simulations.
• Binding free energy calculations and Potential of Mean Force (PMF) analysis.

Main Results:

• Pilocarpine binding affinities were ranked, aligning with experimental data.
• Sequence divergence among CYP2 enzymes dictates distinct major channel usage.
• A gating mechanism involving specific phenylalanine residues (Phe209, Phe116, Phe298) was proposed for channel regulation.

Conclusions:

• Hydrophobic residues act as gatekeepers, controlling channel opening and inhibitor interaction.
• The study provides a molecular basis for understanding variations in CYP isoform activity.
• Findings offer crucial insights for designing potent and selective P450 inhibitors.