The paraoxonase (PON) gene family includes 3 genes, PON1, PON2, and PON3, aligned next to each other on chromosome 7. PON1 (EC 3.1.1.2) hydrolyzes the toxic oxon metabolites of several organophosphorous insecticides, including parathion, diazinon, and chlorpyrifos, as well as nerve agents, such as sarin and soman. PON1 also hydrolyzes aromatic esters, preferably those of acetic acid. In addition, PON1 hydrolyzes a variety of aromatic and aliphatic lactones, and it also catalyzes the reverse reaction, lactonization, of gamma- and delta-hydroxycarboxylic acids. Human PON1 is synthesized in liver and secreted into blood, where it is associated exclusively with high density lipoproteins (HDLs) and may protect against development of atherosclerosis (Draganov et al., 2005).