Atypical Michaelis-Menten kinetics in cytochrome P450 enzymes: A focus on substrate inhibition

Area of Science:

• Biochemistry
• Pharmacology
• Enzyme Kinetics

Background:

• Michaelis-Menten kinetics, established in the 1950s, are extensively applied to study drug-metabolizing cytochrome P450 enzymes.
• Atypical Michaelis-Menten kinetics have been reported, challenging the assumption that they are solely experimental artifacts.

Purpose of the Study:

• To summarize diverse forms of atypical Michaelis-Menten kinetics.
• To highlight the risks associated with using inaccurate hyperbolic models for in vitro-in vivo extrapolation and drug-drug interaction prediction.
• To discuss mechanisms, models, and regulatory roles of these kinetics.

Main Methods:

• Literature review and synthesis of existing research on Michaelis-Menten kinetics and its atypical forms.
• Analysis of postulated mechanisms and kinetic models for cytochrome P450 enzymes.
• Discussion of potential artifactual sources contributing to observed atypical kinetics.

Main Results:

• Atypical Michaelis-Menten kinetics, including biphasic kinetics, cooperativity, and substrate inhibition, are prevalent in cytochrome P450 enzyme studies.
• These deviations necessitate a move beyond simple hyperbolic models.
• Understanding atypical kinetics is vital for accurate prediction of drug interactions and metabolic behavior.

Conclusions:

• The persistence of atypical Michaelis-Menten kinetics in cytochrome P450 research underscores the limitations of traditional models.
• Accurate characterization of enzyme kinetics is essential for reliable in vitro-in vivo extrapolation and drug-drug interaction assessment.
• Further investigation into the mechanisms and implications of atypical kinetics is warranted for improved drug development and safety.