While these oxidations are often of benefit to the body, certain carcinogens and toxins are bioactivated by CYP2E1, implicating the enzyme in the onset of hepatotoxicity caused by certain classes of drugs (see disease relevance section below).

In the conversion sequence of acetyl-CoA to glucose, CYP2E1 transforms acetone via hydroxyacetone (acetol) into propylene glycol and methylglyoxal, the precursors of pyruvate, acetate and lactate.

[15] 19-HETE is an inhibitor of 20-HETE, a broadly active signaling molecule, e.g. it constricts arterioles, elevates blood pressure, promotes inflammation responses, and stimulates the growth of various types of tumor cells; however the in vivo ability and significance of 19-HETE in inhibiting 20-HETE has not been demonstrated.

CYP2E1 exhibits structural motifs common to other human membrane-bound cytochrome P450 enzymes, and is composed of 12 major α-helices and 4 β-sheets with short intervening helices interspersed between the two.

[14] Like other enzymes of this class, the active site of CYP2E1 contains an iron atom bound by a heme center which mediates the electron transfer steps necessary to carry out oxidation of its substrates.

[25][26] A number of residues proximal to the active site including L368 help make up a constricted, hydrophobic access channel which may also be important for determining the enzyme's specificity towards small molecules and ω-1 hydroxylation of fatty acids.

CYP2E1 expression is easily inducible, and can occur in the presence of a number of its substrates, including ethanol,[22] isoniazid,[22] tobacco,[29] isopropanol,[6] benzene,[6] toluene,[6] and acetone.

[6] The oxidation of these molecules by CYP2E1 can produce harmful substances such as trifluoroacetic acid chloride from halothane [31] or NAPQI from paracetamol (acetaminophen) and is a major reason for their observed hepatotoxicity in patients.

CYP2E1 and other cytochrome P450 enzymes can inadvertently produce reactive oxygen species (ROS) in their active site when catalysis is not coordinated correctly, resulting in potential lipid peroxidation as well as protein and DNA oxidation.

Starvation appears to upregulate CYP2E1 mRNA production in liver cells while alcohol seems to stabilize the enzyme itself post-translation and thus protect it from degradation by normal cellular proteolytic processes, giving the two an independent synergistic effect.