engleski

Distribution of paraoxonase activities and phenotypes in a healthy population group from the Slavonski Brod area

Paraoxonase (EC 3.1.8.1) is an esterase that hydrolyses paraoxon (O, O-diethyl-4-nitrophenylphosphate) but has also some arylesterase activity. Recent studies have suggested that paraoxonase associated with serum HDL could protect LDL against peroxidation and thus is involved in the antiatherogenic properties of HDL. Studies of many populations have shown that paraoxonase serum activities in humans have a distribution characteristic of two alleles, one with low (AA) and the other with high (BB) activity. We investigated paraoxonase and arylesterase activity of the enzyme in sera of 145 healthy blood donors from the area of Slavonski Brod, Croatia. The paraoxonase activity was measured at 37 0C with 2 mM paraoxon in the absence and in the presence of 1 M NaCl, and with 5 mM phenylacetate. The distribution of paraoxonase activities in the absence of NaCl was trimodal and the activities ranged between 55 and 611 U/L while salt-stimulated activities ranged between 93 and 1437 U/L. The arylesterase activities ranged between 28 and 215 U/mL and the distribution was unimodal. Using the double substrate method, e.g. the ratio of paraoxon activity in the presence of NaCl vs. phenylacetate activity, the phenotype profile of the population was determined. There were 39 % individuals were classified as AA homozygous low activity group, 55% as heterozygous AB phenotype and 6% as BB homozygous high activity group. This distribution was similar to the other paraoxonase phenotype distribution found in other European populations. Along with the enzyme activity the concentration of lipids and lipoproteins in sera was determined. Total cholesterol, LDL-cholesterol, triglycerides and HDL-cholesterol concentration fell within the reference range of Croatian population. There was no significant correlation between paraoxonase or arylesterase activities and HDL-cholesterol in any of the three phenotype groups.

paraoxonase; arylesterase; paraoxonase/arylesterase ratio

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