Plasma lipoproteins: composition, structure and biochemistry - 0 views
lipidlibrary.aocs.org/...index.htm
apolipoproteins cholesterol VLDL chylomicrons LDL HDL lipoproteins biochemistry
shared by Nathan Goodyear on 21 May 13
- No Cached
-
triacylglycerols
-
The most abundant lipid constituents are triacylglycerols, free cholesterol, cholesterol esters and phospholipids (phosphatidylcholine and sphingomyelin especially ), though fat-soluble vitamins and anti-oxidants are also transported in this way
-
the lipoprotein aggregates should be described in terms of the different protein components or apoproteins (or 'apolipoproteins'
- ...8 more annotations...
-
these classes can be further refined by improved separation procedures, and intermediate-density lipoproteins (IDL) and subdivisions of the HDL (e.g. HDL1, HDL2, HDL3 and so forth
-
Density is determined largely by the relative concentrations of triacylglycerols and proteins and by the diameters of the broadly spherical particles
-
Lipoproteins are spherical (VLDL, LDL, HDL) to discoidal (nascent HDL) in shape with a core of non-polar lipids, triacylglycerols and cholesterol esters, and a surface monolayer, ~20Å thick, consisting of apoproteins, phospholipids and non-esterified cholesterol, which serves to present a hydrophobic face to the aqueous phase
-
the various lipid components should not be considered as absolute, as they are in a state of constant flux
-
Apo A1 is the main protein component of HDL
-
Apo A2 is the second most important HDL apolipoprotein
-
the main groups are classified as chylomicrons (CM), very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL), based on the relative densities of the aggregates on ultracentrifugation
-
The lipoproteins can be categorised simplistically according to their two main metabolic functions. The principal role of the chylomicrons and VLDL is to transport triacylglycerols ‘forward’ as a source of fatty acids from the intestines or liver to the peripheral tissues. In contrast, the HDL remove excess cholesterol from peripheral tissues and deliver it to the liver for excretion in bile in the form of bile acids (‘reverse cholesterol transport’). While these functions are considered separately here for convenience, it should be recognised that the processes are highly complex and inter-related, and they involve transfer of apoproteins, enzymes and lipid constituents among the heterogeneous mix of all the lipoprotein fractions.
-
Awesome review of apolipoproteins, their function, and their metabolism.