MALDI-MS Determination of Apolipoprotein Molecular Stoichiometry in Native High Density Lipoprotein Sub-fractions

摘要

The data disclose that the native LpAI particles consist of 2AI, 3AI and 4AI molecules when the size shifts from small to large. Similarly, LpAIAII contains particles with (2AI+1AII), (2AI+2AII) and (2AI+3AII). In addition, the data indicate that each of the above particles exists with an additional single molecule of apoC-III as well. About two thirds of native HDL is LpAIAII in which the (2A1+2AII) particles are found to be the most prominent population. As the particle size shifts from small to large, a considerable amount of monomeric apoA-I can be seen in the spectra. This can be due to the fact that protein molecules are far apart in larger HDL. Compositional analysis indicated that the larger particles have significant differences in composition including more TG and total protein in LpAIAII. Experiments to determine functional properties of these HDL sub-fractions towards lipases are currently underway.