Phase II drug metabolizing enzyme

Phase II drug metabolizing enzymes comprise a group of broad-specificity conjugating enzymes, mainly transferases, that add polar endogenous groups (such as glucuronic acid, sulfate, acetyl, methyl, and glutathione) to drugs, xenobiotics, or endogenous toxic compounds, rendering them more hydrophilic and readily excretable. The primary families include UDP-glucuronosyltransferases, sulfotransferases, N-acetyltransferases, glutathione S-transferases, and methyltransferases. These enzymes are essential for the detoxification and clearance of both endogenous and exogenous substrates. Genetic polymorphisms in several phase II enzymes (e.g., NAT2, GSTs) can significantly influence individual responses to drugs and susceptibility to some diseases, such as certain cancers and drug toxicities. "Phase II enzyme" is not a single molecular target or protein, but rather an umbrella term for many specific enzymes with related—though distinct—functions[1][2][3][5][4][6].

Other names

Phase II enzymesconjugation enzymesphase II DMEsdrug conjugating enzymestransferases (includes distinct enzyme families: UDP-glucuronosyltransferase, sulfotransferase, N-acetyltransferase, glutathione S-transferase, methyltransferase)

Conjugation/inactivation (through glucuronidation, sulfation, acetylation, methylation, glutathione conjugation); Polymorphic metabolism (variability due to genetics leading to increased/decreased drug levels)