Abstract 587: Dynamics of the Apolipoproteome: Turnover of HDL- and LDL-Associated Apolipoproteins by LC/MS/MS

The production rate and fractional catabolic rate of apoB and apoAI have been measured using stable isotope infusions of 13C or 2H leucine for many years and has led to our improved understanding of the pathophysiology of dyslipidemia and atherosclerosis. Modern tandem mass spectrometry methods have demonstrated the highly complex complement of proteins that associate with HDL and LDL and alterations in these proteins may impact lipoprotein function and cardiovascular risk. Very little is known about the turnover of the proteins that comprise the apolipoproteome. To study the fesability of measuring the turnover of multiple apolipoproteins associated with HDL and LDL we performed 20 hour IV infusions of U-13C labeled leucine in 20 healthy subjects. VLDL, LDL and HDL were isolated by ultracentrifugation and digested with trypsin. We analyzed peptides containing one leucine with analysis of multiple transitions using an Agilent triple quad. The enrichment of HDL and LDL peptides from multiple apolipoprotein...