[Determination of paraoxonase activities in serum and HDL]

[corrected] To establish a reliable method of determining the activity of paraoxonase(PON) in serum and high density lipoprotein(HDL).

We used phenylacetate(PA) as substrate and investigated the hydrolysis of PA catalyzed by serum PON or HDL-PON. The PON activities were calculated from the velocities of reaction that had been determined by the increasing absorbance of product p-phenol within the first 5 minutes.

Through the studies on the effects of substrate concentration, pH, activator Ca2+, and inhibitor EDTA, we found the best conditions of reaction to be: substrate concentration 5 mmol/L, pH8.0, and Ca2+ concentration 2 mmol/L. And we established the method with good reproducibility and stability.

Under the above-stated conditions, it is reliable to determine the activity of paraoxonase in serum and HDL.