NEW YORK, N.Y. and HAIFA, Israel, April 14, 1998 -- A little-known enzyme may play a significant role in preventing heart attack. A paper appearing April 15 in the prestigious Journal of Clinical Investigation, reports that paraoxonase, an enzyme present in the blood, prevents the oxidation of low-density lipoprotein or LDL, the "bad cholesterol" that is deposited in blood vessels and leads to coronary heart disease. The paper is by Professor Michael Aviram, a biochemist, head of the Lipid Research Laboratory, Faculty of Medicine at the Technion-Israel Institute of Technology and at Rambam Medical Center in Haifa, Israel.
"Paraoxonase is located in the blood on the HDL, the 'good' cholesterol, and it can break down oxidized LDL to non-harmful products," explains Aviram, adding that the discovery of this enzyme's activity opens a possible new route to prevention of heart diseases.
The real function of the enzyme has been something of a mystery since it was discovered more than 40 years ago. Its previously known function was to break down organophosphates, chemicals that are used as insecticides and poison gases. That activity was obviously not the complete story of paraoxonase, as humans do not normally contain these substances in their blood, Aviram realized.
Since the major focus of his past research has been the study of the mechanisms by which oxidized cholesterol and other oxidized lipids accumulate in arterial wall cells, leading to blockage of arteries and formation of atherosclerotic lesions, he decided to study the effect of the enzyme on oxidized lipids. Researchers had previously found a very strong inverse relationship between the activity of paraoxonase in the blood and the risk of heart disease. Lower activity is associated with higher risk. The present study helps us understand the mechanism behind that relationship.
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Contact: Martha Molnar
American Society for Technion - Israel Institute of Technology