Cross-Reaction of a Human Anti-Paraoxonase Monoclonal Antibody with a Rat High Density Lipoprotein Peptide
During recent studies, monoclonal antibodies raised against human high density lipoproteins (HDL) identified a protein with a molecular mass of 45 kD (range 42–48 kD) and with a pI of 4.5–4.9. Aminoterminal sequence analysis showed the protein to correspond to human paraoxonase  (aryldialkylphosphatase E.C. 18.104.22.168), an enzyme which can hydrolyse and detoxify organophosphate compounds such as the activated form of the insecticide parathion . The enzyme has been recently cloned from human and rabbit cDNA libraries . Paraoxonase seems to be a highly conserved protein: 85 % of amino acids are identical and up to 94 % are similar between the 2 species. Despite the fact that it exhibits relatively high activity in the sera of all mammals , the natural substrate(s) as well as the physiological function(s) of paraoxonase remain obscure. The potential importance of paraoxonase in protecting against organophosphate toxicity is recognised, but it is not known whether this relates to the true function of the enzyme. The association of paraoxonase with HDL [5–7] has led to suggestions that the enzyme could have a function related to lipid metabolism. In recent studies, we demonstrated that human paraoxonase is a marker of a distinct subpopulation of HDL composed essentially of 3 proteins: paraoxonase, apolipoprotein (apo) AI, and to a lesser extent, clusterin, also called apo J .
KeywordsHigh Density Lipoprotein Coomassie Staining eDNA Library Human High Density Lipoprotein Organophosphate Toxicity
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