glyoxalase

Glyoxalase refers to a cellular detoxification system that neutralizes reactive dicarbonyl compounds, most notably methylglyoxal (MG), a byproduct of glycolysis and other metabolic pathways. MG can modify proteins and nucleic acids, contributing to cellular damage and aging-related processes. The glyoxalase system typically uses glutathione and a two-enzyme sequence to convert MG into the less reactive metabolite D-lactate.

In the classical glyoxalase pathway, MG spontaneously forms a hemithioacetal with glutathione (GSH). Glyoxalase I (Glo1) converts this intermediate to S-D-lactoylglutathione, and glyoxalase II (Glo2) hydrolyzes it to D-lactate, regenerating GSH. The D-lactate can then enter central metabolism or be further metabolized. This two-step, GSH-dependent route operates primarily in the cytosol of many organisms and helps maintain redox balance.

Glyoxalase III (Glo3) denotes a GSH-independent, single-step conversion of MG to D-lactate found in some organisms. Glo3 activity is often associated with members of the DJ-1/ThiJ/PfpI superfamily and varies in presence and mechanism across species, providing an alternative detoxification route when GSH is limited.

Distribution and regulation: Glyoxalases are found in bacteria, plants, fungi, and animals, with tissue- and compartment-specific expression patterns. Expression and activity are typically induced by MG exposure and oxidative stress, linking the pathway to cellular defense and metabolic state.

Physiological relevance: Efficient MG detoxification by the glyoxalase system protects cells from carbonyl stress and influences aging, diabetic complications, neurodegenerative diseases, and cancer biology. As a result, components of the glyoxalase system are active areas of biomedical research, including studies of modulation for therapeutic benefits.