Petar Alaupovic: The father of lipoprotein classification based on apolipoprotein composition.

etar Alaupovic, an internationally renowned biochemist and lipidologist, died on January 30, 2014, in Oklahoma City at the age of 91 years. Dr Alaupovic was a founder of the modern field of lipoproteins whose ideas continue to have an impact on its development. He performed research and taught at Oklahoma Medical Research Foundation since 1960. In 1964, Dr Alaupovic, known to his colleagues as Dr A or Pierre, proposed a revolutionary new classification system for lipoproteins. Until that time, the classification of lipoproteins focused on the physical properties of lipoproteins, emphasizing the lipid component and the size of the lipoprotein particle. However, Dr Alaupovic considered the protein part to have great biological importance that directed every step in the metabolism of lipoproteins and determined their effects on atherosclerosis. When he began his research on lipoproteins, there were considered to be just 2 apolipoproteins, apolipopro-tein B and apolipoprotein A. Using immunologic and protein chemistry techniques, he isolated and characterized several additional apolipoproteins associated with lipoproteins. He proposed the ABC nomenclature for apolipoproteins, which initially included apolipoproteins A-I, A-II, B, C-I, C-II, C-III, D, and E. Most important to the subsequent progress in the field of lipoprotein, he subdivided the major lipopro-tein classes, apolipoprotein A-I and apolipoprotein B lipopro-teins, according to their content of other apolipoproteins that, although not required for their formation and secretion, confer specific crucial functions to lipoproteins. Thus, a second major change in his classification system from the prevailing view of lipoproteins at that time was the concept that there were separate and distinct lipoprotein particles or families with defined apolipoprotein composition within the major density classes of very-low-density, intermediate-density, low-density, and high-density lipoproteins. Dr Alaupovic hypothesized that apolipoprotein E and the apolipoprotein Cs are not randomly scattered among all the apolipoprotein B and apolipoprotein A-I lipoproteins but are focused on specific subfractions that comprise a percentage of the total. He divided apolipoprotein B into lipoprotein B:E (containing apolipoproteins B and E), lipoprotein B:C-III (containing apolipoproteins B and C-III), lipoprotein B:E:CIII (containing apolipoproteins B, E, and C-III), and lipoprotein B (containing apolipoproteins B, but not apolipoprotein E or C-III). Dr Alaupovic showed that these lipoprotein subtypes have specific functions and relation to atherosclerosis. Thus, Dr Alaupovic conceived the concept and demonstrated the biological and clinical importance of lipoprotein speciation. These radical changes in the concepts of the heterogene-ity of plasma apolipoproteins and lipoproteins and the need for the …