Effect of the molecular polymorphisms of human paraoxonase (PON1) on the rate of hydrolysis of paraoxon

Abstract
The hydrolysis of organophosphate pesticides (OP) and nerve gases by serum paraoxonase (PON1) is an important factor determining their toxicity to mammals including man. The PON1 gene contains 2 polymorphic sites at amino acid positions 55 (L→M) and 192 (G→A, classically defined as the A and B genotypes) which result in several alloenzymes of PON1 in human serum. The 192 polymorphism has previously been shown to affect PON1 activity. We have investigated the effect of both polymorphisms on the hydrolysis of paraoxon by serum from 279 healthy human subjects. The 55 polymorphism significantly influenced PON1 activity. MM homozygotes had over 50% less activity towards paraoxon compared to the LL and LM genotypes regardless of the 192 genotype (PPBritish Journal of Pharmacology (1997) 122, 265–268; doi:10.1038/sj.bjp.0701390