Glutathione (GSH), due to the ability to capture the reactive electrophiles of exoand endogenous origins, is expected to prevent cross-linking induced by these compounds. However, it may instead become cross-linked itself. We subjected glutathione to reactions with model α,β-unsaturated carbonyl systems resulting from the interactions of adenosine with bifunctional aldehyde products of lipid peroxidation, and identified a range of adducts and cross-linked products. We found that the S-conjugated adducts, initially formed in the typical GSH Michael addition to α,β-unsaturated carbonyl system, unexpectedly undergo gradual degradation giving rise to the final N-conjugated products, in which formation of peptide amino group is involved instead of sulfhydryl functionality. This finding shows that the role of the GSH amino group in the non-enzymatic detoxification is underestimated, and that reactions between cellular α,β-unsaturated carbonyl compounds and GSH may be more complex than are presently perceived.