Beneficial effect of oleoylated lipids on paraoxonase 1: protection against oxidative inactivation and stabilization

Biochem J. 2003 Oct 15;375(Pt 2):275-85. doi: 10.1042/BJ20030663.


The effect of lipids on PON1 (paraoxonase 1), one of antioxidant proteins in high-density lipoprotein, was investigated in respect to inhibition, protection against oxidative inactivation, and stabilization. When the effect of lipids on the PON1 activity was examined, a remarkable inhibition was expressed by polyenoic fatty acids (C18:2-C20:5). Linoleic acid, the most potent ( K(i), 3.8 microM), showed competitive inhibition. Next, various lipids were examined for prevention against the inactivation of PON1 by ascorbate/Cu2+, which caused a remarkable (>or =90%) inactivation of PON1. Compared with saturated fatty acids (C6-C18), exhibiting a modest protection (9-40%), monoenoic acids (C16:1-C20:1) showed a greater maximal protective effect (Emax, 70-82%), with oleic acid being the most effective (EC50, 2.7 microM). In contrast, polyenoic acids showed no protection. Noteworthy, linoleic acid prohibited the protective action of oleic acid non-competitively. In the structure-activity relationship, a negatively charged group seems to be required for the protective action. Consistent with this, dioleoylphosphatidylglycerol, negatively charged, was more protective than dioleoylphosphatidylcholine. These data, together with requirement of Ca2+ (EC50, 0.6 microM) for the protective action, may support the existence of a specific site responsible for the protective action. A similar protective action of lipids was also observed in the inactivation of PON1 by ascorbate/Fe2+, peroxides or p -hydroxymercuribenzoate. Separately, PON1 was stabilized by oleic acid or oleoylated phospholipids, in combination with Ca2+, but not linoleic acid. These results suggest that in contrast to an adverse action of linoleic acid, monoenoic acids or their phospholipid derivatives play a beneficial role in protecting PON1 from oxidative inactivation as well as in stabilizing PON1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aryldialkylphosphatase / metabolism*
  • Ascorbic Acid / pharmacology
  • Copper / pharmacology
  • Dose-Response Relationship, Drug
  • Enzyme Activation / drug effects
  • Enzyme Stability / drug effects
  • Fatty Acids / pharmacology
  • Humans
  • Hydroxymercuribenzoates / pharmacology
  • Kinetics
  • Oleic Acid / pharmacology*
  • Oxidants / pharmacology
  • Oxidation-Reduction
  • Phospholipids / pharmacology*
  • Protease Inhibitors / pharmacology


  • Fatty Acids
  • Hydroxymercuribenzoates
  • Oxidants
  • Phospholipids
  • Protease Inhibitors
  • 4-hydroxymercuribenzoate
  • Oleic Acid
  • Copper
  • Aryldialkylphosphatase
  • Ascorbic Acid