CYP2E1 and ROS
What it is
Cytochrome P450 2E1 — a high-capacity, low-affinity ethanol-metabolising enzyme. Dominates when BAC is high (>20 mM) or ADH is saturated.
Key kinetic parameters
- Km = 8–10 mM (lower affinity than class I ADH at 0.2–2.0 mM)
- At high ethanol (40–70 mM): CYP2E1 accounts for 70–100% of metabolism
- Inducible: expression increases with chronic drinking, fasting
- Generates 2 NADH per ethanol (like ADH) + ROS
ROS production
CYP2E1 transfers electrons from NADH/NADPH to O₂, producing:
- Superoxide anion radical (O₂⁻)
- Hydrogen peroxide (H₂O₂)
- Hydroxyl radical (OH•) in presence of iron (Fenton chemistry)
The hangover pathway
Ethanol → CYP2E1 → ROS → NF-κB activation → IL-6, TNF-α, CRP → hangover symptoms
↘
Intestinal barrier disruption → endotoxin (LPS) → Kupffer cells → TNF-α
CYP2E1 and gut barrier
- Ethanol + CYP2E1 → nitroxidative stress in intestinal epithelium
- Damaged gut barrier → bacterial endotoxin translocates to portal circulation
- Endotoxin activates hepatic Kupffer cells via TLR4 → TNF-α release
- This is the primary systemic inflammatory driver of hangover
Brain CYP2E1
- CYP2E1 present in neurons and glia (cerebellum, cortex, thalamus, hippocampus)
- Brain-local CYP2E1 produces acetaldehyde in situ — does NOT come from blood
- CYP2E1-null mice have longer ethanol sleep times, confirming its role in CNS ethanol metabolism
Vitals implication
CYP2E1 induction is the rate-limiting step for hangover severity in moderate-to-heavy drinkers. Wearable biometric disruption proportional to individual CYP2E1 activity level.