الفهرس 
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Abstract
mma lipoproteins
Structure and Oassification :-
The plasma lipoproteins are water-soluble macromolecular complexes that
transportvarious lipids in the blood and other tissue fluids’!’, These particles of
lipoproteinare composed of fatty core of cholesteryl esters and triglycerides
surroundedby a monolayer of phosphilipids and free cholesterol, also there is a
typeof protein is embedded in this core colled apoprotein. The protein part binds
to lipidin a loosely manner to allow the ready exchang of lipids among serum
lipoproteinand between serum and tissue lipoprotein’v”, but the binding between
the apoprotein and lipids is tight enough to permit the lipoproteins complex to
separatebyusing analytical techniques!”, Traditionally the plasma lipoproteins have
beenseparated by ultracentrifugal flotation into five major density classes (Table
1). Theincidenceof coronary heart disease has been positively correlated with high
levelsof LDL-cholesterol and negatively correlated with high levels of HOLcholesterol’’:”.
The protein components of plasma lipoproteins are known as apolipoproteins.
The major function of apolipoproteins is lipid transport in the intravascular
andextravascularcompartments. Many apolipoproteins have, in addition, acquired
highlyspecializedfunctions. For example, Goldstein and Brown” have shown that
LDLinteractswith cell-surface receptors, thereby regulating cholesterol biosynthesis
andmetabolism’”. The major apolipoprotein in LOL is apolipoprotein B (apoB).