Date post: | 06-Feb-2015 |
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LIPOPROTEIN AND CHOLESTEROL
Angel Das 1 year MBBS Student
LIPOPROTEIN
Lipid
Protein
Lipoprotein
CORE
CHOLESTEROLESTERS
TRIGLYCERIDES
MONOLAYER OF PHOSPHOLIPID
AND CHOLESTERLOL
INTEGRAL APOPROTEINS
PERIPHERAL APOPROTEINS
Structure of lipoprotein
APOPROTEINS
Protein component of lipoproteinPromote transport and uptake of lipids
Act as ligandActivation of enzymes
APOPROTEINS
A B C E• A-l• A-ll
• B-48• B-100
• C-l• C-ll• C-lll
• A-I Liver& intestine
• A-II Liver
• B-48 Intestine• B-100 Liver
• All Liver • Liver
LIPOPROTEINS Lipoprotein Apoproteins
Chylomicron A,B,C,E
VLDL B,C,E
LDL B
HDL A,C,D, E
CLASSIFICATION
Based on density by ultracentrifugationi. Chylomicronsii. Very Low Density Lipoproteiniii.Intermediate Density Lipoproteiniv.Low Density Lipoproteinv. High Density Lipoprotein
COMPOSITION AND SIZE OF LIPOPROTEIN
FUNCTIONS OF LIPOPROTEINS
CHYLOMICRONS transport Triglycerides from intestine to adipose tissues for storage.VLDL carries triglycerols from liver to peripheral tissues.
LDL transports cholesterol from liver to peripheral tissues.HDL transports cholesterol from peripheral tissues to liver“Reverse Cholesterol Transport”
CLINICAL SIGNIFICANCE
HYPERLIPIDEMIAS elevated lipid fraction cholesterol/TAG Frederickson’s Classification
Type l Type ll A Type ll B Type lll Type lV Type V
Type Lipoprotein fraction elevated
Metabolic Defect
Type ll A (Primary Familial Hypercholesterolemia)
LDL LDL receptor defect
Type ll B Hyperlipoproteinemia
LDL & VLDL Apo B
Type lV Familial endogenous Type
VLDL Overproduction of VLDL
HYPOLIPOPROTEINEMIAS
i. Abetalipoproteinemia microsomal triglyceride transfer protein is defective LDL & VLDL decreasesii. Hypo alpha lipoproteinemia HDL level decreasesiii. Tangier Disease absence of ATP binding Cassette Transporter 1, involved in transport of cellular cholesterol to HDL
ATHEROSCLEROSIS
•Deposition of LDL cholesterol in arterial wall, occurs due to damage of endothelium
Physical Properties white crystalline solid substance soluble in ether,chloroform etc. amphipathic in nature abundantly present in nervous tissue
•Have Cyclopentanoperhydrophenanthrene ring system.
CHOLESTEROL
STRUCTURE OF CHOLESTEROL
1. Major structural constituent of the cell membranes and lipoproteins
2. Precursor for Steroid hormones
a. Progesterons
b. Glucocorticoids
c. Mineralocorticoids
d. Androgens & Estrogens
3. Formation of Bile acids and bile salts.
4. Synthesis of Vitamin D
FUNCTIONS OF CHOLESTEROL