| Abstract
| - In order to isolate pre-β1 HDL, we have focused ourinterest on a particular model, namely,human preovulatory follicular fluid, which contains only HDL as alipoprotein class as well as a highproportion of pre-β1 HDL relative to total HDL (1.5 timesmore than in homologous plasma) as evidencedby double-dimension gel electrophoresis. Apo A-I inpre-β1 HDL represented 17.6% of total apoA-I.Stokes' radii corresponded to 3.42 nm in follicular fluidpre-β1 HDL and 3.48 nm in homologous plasmacounterparts. After electroelution from agarose,pre-β1 HDL were isolated in amounts sufficient toallowcharacterization by size-exclusion chromatography using HPLC. Theestimated apparent molecular massof these particles is 61.6 kDa. Lipid composition ofpre-β1 HDL evidenced a low lipid contentcomparedto follicular fluid HDL isolated by ultracentrifugation.Phospholipid composition showed a dramaticdecrease in phosphatidylcholines (40.5% of total phospholipids), andthe presence of lysophosphatidylcholines and of acidic phospholipids such as phosphatidylserine andphosphatidylinositol (13.6 and 13.7%,respectively). Furthermore, cholesteryl ester and triacylglycerolmolecules were quantified by gas−liquidchromatography and represented 8−9% of the pre-β1 HDLtotal weight. Thus, a lipid core is present inpre-β1 HDL, which would be compatible with a sphericalshape. The follicular fluid appears to be agood model to a better understanding of HDL metabolism.
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