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J Lipid Res. 2007 Jul;48(7):1637-46. Epub 2007 Apr 13.

The development of human sera tests for HDL-bound serum PON1 and its lipolactonase activity.

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Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.


Serum paraoxonase (PON1) is a lipolactonase that associates with HDL-apolipoprotein A-I (HDL-apoA-I) and thereby plays a role in the prevention of atherosclerosis. Current sera tests make use of promiscuous substrates and provide no indications regarding HDL-PON1 complex formation. We developed new enzymatic tests that detect total PON1 levels, irrespective of HDL status and R/Q polymorphism, as well as the degree of catalytic stimulation and increased stability that follow PON1's tight binding to HDL-apoA-I. The tests are based on measuring total PON1 levels with a fluorogenic phosphotriester, measuring the lipolactonase activity with a chromogenic lactone, and assaying the enzyme's chelator-mediated inactivation rate. The latter two are affected by tight HDL binding and thereby derive the levels of the serum PON1-HDL complex. We demonstrate these new tests with a group of healthy individuals (n=54) and show that the levels of PON1-HDL vary by a factor of 12. Whereas the traditionally applied paraoxonase and arylesterase tests weakly reflect PON1-HDL levels (R=0.64), the lipolactonase test provides better correlation (R=0.80). These new tests indicate the levels and activity of PON1 in a physiologically relevant context as well as the levels and quality of the HDL particles with which the enzyme is associated.

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