Deglycase that catalyzes the deglycation of the Maillard adducts formed between amino groups of proteins and reactive carbonyl groups of glyoxals. Thus, functions as a protein deglycase that repairs methylglyoxal- and glyoxal-glycated proteins, and releases repaired proteins and lactate or glycolate, respectively. Deglycates cysteine, arginine and lysine residues in proteins, and thus reactivates these proteins by reversing glycation by glyoxals. Acts on early glycation intermediates (hemithioacetals and aminocarbinols), preventing the formation of advanced glycation endproducts (AGE) that cause irreversible damage (By similarity). Also displays proteolytic activity (PubMed:11114201). H2O + N(omega)-(1-hydroxy-2-oxopropyl)-L-arginyl-[protein] = H(+) + L-arginyl-[protein] + lactate H2O + N(6)-(1-hydroxy-2-oxopropyl)-L-lysyl-[protein] = H(+) + L-lysyl-[protein] + lactate H2O + S-(1-hydroxy-2-oxopropyl)-L-cysteinyl-[protein] = H(+) + L-cysteinyl-[protein] + lactate H2O + N(omega)-(1-hydroxy-2-oxoethyl)-L-arginyl-[protein] = glycolate + H(+) + L-arginyl-[protein] H2O + N(6)-(1-hydroxy-2-oxoethyl)-L-lysyl-[protein] = glycolate + H(+) + L-lysyl-[protein] H2O + S-(1-hydroxy-2-oxoethyl)-L-cysteinyl-[protein] = glycolate + H(+) + L-cysteinyl-[protein] Homohexamer formed by a dimer of trimers that assemble into a hollow ring structure. Belongs to the peptidase C56 family.