[Paraoxonase: its multiple functions and pharmacological regulation].

Homocysteine, a non-protein amino acid, important risk factor for atherosclerosis and thrombosis, causes dysfunction of vascular endothelial cells traduced in inadequate vasodilatation mechanism, is pro-inflammatory and induces endoplasmic reticulum stress. The more reactive conformation is the homocysteine thiolactone (HcyT), product to the nonspecific action of methionyl-tRNA synthetase, which is incorporated into proteins by disulfide bonds (S-homocysteinilation) or amide bonds (N-homocysteinilation) affecting protein structure and function leading to cell toxicity, autoimmune responses and atherogenesis. The enzyme paraoxonase-1 (PON1), part of high density lipoprotein (HDL), had been studied only for its ability to hydrolyze organophosphate derivatives.