Serum paraoxonase/arylesterase 1 (PON1) also known as aromatic esterase 1 or serum aryldialkylphosphatase 1 is an enzyme that in humans is encoded by the PON1 gene. Paraoxonase 1 has esterase and more specifically paraoxonase activity.
PON1 is responsible for hydrolysing organophosphate pesticides and nerve gasses. Polymorphisms in the PON1 gene significantly affect the catalytic ability of the enzyme.
PON1 (paraoxonase 1) is also a major anti-atherosclerotic component of high-density lipoprotein (HDL). The PON1 gene is activated by PPAR-γ, which increases synthesis and release of paraoxonase 1 enzyme from the liver, reducing atherosclerosis.