Biochemical characterization of pre-beta 1 high-density lipoprotein from human ovarian follicular fluid: evidence for the presence of a lipid core.
In order to isolate pre-beta 1 HDL, we have focused our interest on a particular model, namely, human preovulatory follicular fluid, which contains only HDL as a lipoprotein class as well as a high proportion of pre-beta 1 HDL relative to total HDL (1.5 times more than in homologous plasma) as evidenced by double-dimension gel electrophoresis. Apo A-I in pre-beta 1 HDL represented 17.6% of total apo A-I. Stokes' radii corresponded to 3.42 nm in follicular fluid pre-beta 1 HDL and 3.48 nm in homologous plasma counterparts. After electroelution from agarose, pre-beta 1 HDL were isolated in amounts sufficient to allow characterization by size-exclusion chromatography using HPLC. The estimated apparent molecular mass of these particles is 61.6 kDa. Lipid composition of pre-beta 1 HDL evidenced a low lipid content compared to follicular fluid HDL isolated by ultracentrifugation. Phospholipid composition showed a dramatic decrease in phosphatidylcholines (40.5% of total phospholipids), and the presence of lysophosphatidylcholines and of acidic phospholipids such as phosphatidylserine and phosphatidylinositol (13.6 and 13.7%, respectively). Furthermore, cholesteryl ester and triacylglycerol molecules were quantified by gas-liquid chromatography and represented 8-9% of the pre-beta 1 HDL total weight. Thus, a lipid core is present in pre-beta 1 HDL, which would be compatible with a spherical shape. The follicular fluid appears to be a good model to a better understanding of HDL metabolism.
Jaspard
B
B
Institut National de la Santé et de la Recherche Médicale, Unité 326, Hôpital Purpan, Toulouse, France.
Collet
X
X
Barbaras
R
R
Manent
J
J
Vieu
C
C
Parinaud
J
J
Chap
H
H
Perret
B
B
D016632:Apolipoprotein A-I / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry*; D053442:High-Density Lipoproteins, Pre-beta; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008075:Lipoproteins, HDL / Q000097:blood / Q000737:chemistry*
D016632:Apolipoprotein A-I; D053442:High-Density Lipoproteins, Pre-beta; D008055:Lipids; D008075:Lipoproteins, HDL