Lipoproteins transport lipids between cells and tissues. They consist of a nonpolar lipid core surrounded by a surface layer of phospholipids and proteins. Lipoproteins are classified based on density into chylomicrons, VLDL, IDL, LDL, and HDL. Chylomicrons transport dietary lipids from the intestine. The liver secretes VLDL, which circulates and is converted to IDL and LDL through lipolysis. HDL transports cholesterol from tissues to the liver. Apolipoproteins associated with each lipoprotein determine its function and metabolism.
Lipid metabolism is the synthesis and degradation of lipids in cells.
It involves the breakdown or storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of cell membranes.
In animals, these fats are obtained from food or synthesized by the liver.
Digestion and absorption of lipids ppt
what is lipid ppt
digestion of lipid ppt
phase of digestion and absorption ppt
phases of lipids ppt
digestion in mouth and stomach ppt
digestion in small intestine ppt
secretion of lipids ppt
enzyme involved in lipid digestion ppt
transportation phases of lipids ppt
principles of lipid digestion ppt
Lipid metabolism is the synthesis and degradation of lipids in cells.
It involves the breakdown or storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of cell membranes.
In animals, these fats are obtained from food or synthesized by the liver.
Digestion and absorption of lipids ppt
what is lipid ppt
digestion of lipid ppt
phase of digestion and absorption ppt
phases of lipids ppt
digestion in mouth and stomach ppt
digestion in small intestine ppt
secretion of lipids ppt
enzyme involved in lipid digestion ppt
transportation phases of lipids ppt
principles of lipid digestion ppt
synthesis and lipolysis is explained in detail. enzymes involved and their differences are tabulated. adipose tissue metabolism is also included. Fatty liver causes are explained in detail. obesity is briefly described.
Lipoprotein metabolism - (transport of lipids in the Blood)Ashok Katta
This presentation explains metabolism of lipoproteins (Chylomicron, VLDL, LDL, HDL) in very simple way. The presentation contains lots of animation to explain metabolism of individual lipoproteins.
A lecture I almost had to give as a 'stand-in' for one of my colleagues. Probably the fastest I've ever prepared a lecture and the first time I have taken someone else's notes and effectively given them a 'presentation make-over. Never did give it but it seems pointless having it sitting around on my hard drive.
At the end of the session he students will be able to learn about definition of lipo proteins, types, composition
Explain its functions of lipo proteins
List out the abnormalities
explain the nursing assessment and lab investigations for identifying defects . explain about treatment for lipo protein deficit
Lipids are insoluble in water, the problem of transportation in the aqueous plasma is solved by associating nonpolar lipids (triacylglycerols and cholesteryl esters) with amphipathic lipids (phospholipids and cholesterol) and proteins to make water-miscible lipoproteins.
lipoproteins transfer lipids such as triacylglycerol, cholestryl ester, fat soluble vitamins in the body. there are 5 categories of lipoproteins which includes chylomicrone, VLDL, IDL, LDL and HDL. LDL-cholesterol is called bad cholestrol while HDL-cholesterol is called good cholesterol.
Lipoprotein introduction, their general characteristics, exogenous and endogenous metabolism focusing on chylomicron and vldl metabolism, ldl metabolism and HDL metabolism , reverse cholesterol transport.
Copper- sources, daily requirement, absorption, transportation, storage, excretion, role in enzymatic action, role in iron metabolism, role in elastin maturation, role in bone formation, copper deficiency, copper toxicity, Wilson disease, Menkes disease.
Folic acid- Chemistry, One carbon metabolism and megaloblastic anemiaNamrata Chhabra
Folic acid- Structure, forms, absorption, transportation, storage, excretion, role in one-carbon metabolism, role in methionine synthesis, role in nucleotide biosynthesis, folate trap, folate antagonists, megaloblastic anemia
Sugar derivatives and reactions of monosaccharidesNamrata Chhabra
Reactions of monosaccharides, osazone formation, reduction, oxidation, reaction with acids and alkalies, ester formation and formation of amino sugars, amino sugar acids and deoxy sugars.
Definition of ELISA, Immunochemical principle of ELISA, Direct, Indirect, Sandwich and Competitive ELISA, applications of ELISA in the diagnostic field, and benefits/drawbacks of ELISA.
Molecular biology revision-Part 3 (Regulation of genes expression and Recombi...Namrata Chhabra
Regulation of gene expression in prokaryotes and eukaryotes, Recombinant DNA technology, Southern hybridization, Northern Hybridization, Western hybridization, cloning, PCR, Applications of RDT, Animal cloning, Multiple choice questions
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
2. Lipids absorbed from the diet and synthesized by the
liver and adipose tissue must be transported between
various cells and organs for utilization and storage.
Lipids are insoluble in water, the problem of
transportation in the aqueous plasma is solved by
associating nonpolar lipids (triacylglycerols and
cholesteryl esters) with amphipathic lipids
(phospholipids and cholesterol) and proteins to make
water-miscible lipoproteins.
3. General Structure of Lipo proteins
Lipoproteins consist of a nonpolar core and a single
surface layer of amphipathic lipids
The nonpolar lipid core consists of mainly
triacylglycerol and cholesteryl ester and is
surrounded by a single surface layer of
amphipathic phospholipid and cholesterol
molecules
These are oriented so that their polar groups face
outward to the aqueous medium.
The protein moiety of a lipoprotein is known as an
apolipoprotein or apoprotein.
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4. General Structure of Lipo proteins
Some apolipoproteins are integral and cannot be removed, whereas others
can be freely transferred to other lipoproteins.
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5. Classification of Lipoproteins
Lipoproteins can be classified in three ways1) Based on density- They are separated by
Ultracentrifugation. Depending upon the floatation
constant (Sf), Five major groups of lipoproteins have
been identified that are important physiologically and
in clinical diagnosis.
(i) Chylomicons, derived from intestinal absorption of
triacylglycerol and other lipids; Density is generally
less than 0.95 while the mean diameter lies between
100- 500 nm
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6. Classification of Lipoproteins
1) Based on density (contd.)
(ii) Very low density lipoproteins (VLDL), derived
from the liver for the export of triacylglycerol;
density lies between 0.95- 1.006 and the mean
diameter lies between 30-80 nm.
(iii) Intermediate density lipoproteins (IDL) are
derived from the catabolism of VLDL,with a density
ranging intermediate between Very low density and
Low density lipoproteins i.e. ranging between 1.0061.019 and the mean diameter ranges between 2550nm.
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7. Classification of Lipoproteins
Based on density (contd.)
iv) Low-density lipoproteins (LDL), representing a
final stage in the catabolism of VLDL; density lies
between 1.019-1.063 and mean diameter lies between
18-28 nm
(iv) High-density lipoproteins (HDL), involved in
cholesterol transport and also in VLDL and
chylomicron metabolism. Density ranges between
1.063-1.121 and the mean diameter varies between 5-15
nm.
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Biochemistry for medics
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8. Classification of Lipoproteins
Lipoproteins with high lipid content will have low density, larger
size and so float on centrifugation. Those with high protein
content sediment easily, have compact size and have a high
density.
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Biochemistry for medics
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9. Classification of Lipoproteins
2) Based on electrophoretic mobilities
Lipoproteins may be separated according to their
electrophoretic properties into - α, pre β, β, and
broad beta lipoproteins.
The mobility of a lipoprotein is mainly dependent
upon protein content.
Those with higher protein content will move faster
towards the anode and those with minimum protein
content will have minimum mobility.
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Biochemistry for medics
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10. Classification of Lipoproteins
Lipoproteins may be separated according to their
electrophoretic properties into - α, pre β, β, and broad
beta lipoproteins.
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Biochemistry for medics
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11. Classification of Lipoproteins
2) Based on electrophoretic mobilities (contd.)
HDL are -α , VLDL pre- β, LDL-β , and IDL are broad
beta lipoproteins.
Free fatty acid and albumin complex although not a
lipoprotein is an important lipid fraction in serum
and is the fastest moving fraction.
Chylomicrons remain at the origin since they have
more lipid content.
VLDLs with less protein content than LDL move
faster than LDL, this is due to nature of apoprotein
present.
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Biochemistry for medics
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12. Classification of Lipoproteins
As the lipid content increases, density decreases and size increases, that
is why Chylomicrons are least dense but biggest in size, while HDL are
rich in proteins , hence most dense but smallest in size.
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Biochemistry for medics
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13. Classification of Lipoproteins
3) Based on nature of Apo- protein content
One or more apolipoproteins (proteins or polypeptides)
are present in each lipoprotein.
The major apolipoproteins of HDL (α-lipoprotein) are
designated A.
The main apolipoprotein of LDL (β -lipoprotein) is
apolipoprotein B (B-100), which is found also in VLDL.
Chylomicons contain a truncated form of apo B (B-48)
that is synthesized in the intestine, while B-100 is
synthesized in the liver.
Apo E is found in VLDL, HDL, Chylomicons, and
chylomicron remnants.
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Biochemistry for medics
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14. Functions of Apo proteins
(1) They can form part of the structure of the
lipoprotein, e.g. apo B, structural component of VLDL
and Chylomicons
(2) They are enzyme cofactors, e.g. C-II for lipoprotein
lipase, A-I for lecithin: cholesterol acyl transferase
(LCAT), or enzyme inhibitors, eg, apo A-II and apo CIII for lipoprotein lipase, apo C-I for cholesteryl ester
transfer protein
(3) They act as ligands for interaction with lipoprotein
receptors in tissues, e.g. apo B-100 and apo E for the
LDL receptor, apo A-I for the HDL receptor.
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15. Metabolism of chylomicrons
Chylomicrons are found in chyle formed only by the
lymphatic system draining the intestine.
They are responsible for the transport of all dietary lipids
into the circulation.
Synthesis of Chylomicrons
1) Synthesis of Apo B48
Chylomicrons contain Apo B48, synthesized in the
rough endoplasmic reticulum (RER).
The synthesis of apo B48 is the result of RNA editing
process.
Coding information can be changed at the mRNA level
by RNA editing.
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16. Synthesis of Chylomicrons
The synthesis of apo B48 is the result of RNA editing
process.
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Biochemistry for medics
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17. Metabolism of chylomicrons
Synthesis of Chylomicrons
In liver, the single apo B gene is transcribed into an mRNA
that directs the synthesis of a 100-kDa protein, apoB100.
In the intestine, the same gene directs the synthesis of the
primary transcript; however, a Cytidine deaminase
converts a CAA codon in the mRNA to UAA at a single
specific site.
Rather than encoding glutamine, this codon becomes a
termination signal, and a 48-kDa protein (apoB48) is the
result.
ApoB100 and apoB48 have different functions in the two
organs
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18. Metabolism of chylomicrons
Apolipoprotein B,
synthesized in the
RER, is incorporated
into lipoproteins in the
SER, the main site of
synthesis of
triacylglycerol.
After addition of
carbohydrate residues
in G, they are released
from the cell by reverse
pinocytosis.
Chylomicrons pass
into the lymphatic
system.
Clinical Significance- In Abetalipoproteinemia (a rare disease),
lipoproteins containing apo B are not formed and lipid droplets
accumulate in the intestine and liver(Due to non formation of VLDL)
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Biochemistry for medics
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19. Synthesis of Chylomicrons (contd.)
2) Synthesis of lipids and formation of lipoprotein
Long-chain fatty acids are esterified to yield to triacylglycerol in
the mucosal cells and together with the other products of lipid
digestion, are incorporated into lipoproteins in the SER, the
main site of synthesis of triacylglycerol.
3) Addition of Carbohydrate-Carbohydrate residues are added
in the golgi apparatus.
4) Release of Chylomicrons- After addition of carbohydrate
residues in golgi apparatus, they are released from the cell by
reverse pinocytosis.
5) Transportation of Chylomicrons- Chylomicrons pass into the
lymphatic system and eventually enter the systemic circulation.
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20. Catabolism of Chylomicrons
Chylomicrons are acted upon by the enzyme
lipoprotein lipase .
Reaction with lipoprotein lipase results in the
loss of approximately 90% of the triacylglycerol of
chylomicrons and in the loss of apo C (which
returns to HDL) but not apo E, which is retained.
The resulting chylomicron remnant is about
half the diameter of the parent chylomicron and
is relatively enriched in cholesterol and
cholesteryl esters because of the loss of
triacylglycerol.
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Biochemistry for medics
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21. Catabolism of Chylomicrons
Chylomicron remnants are taken up by the liver by
receptor-mediated endocytosis, and the cholesteryl
esters and triacylglycerols are hydrolyzed and
metabolized.
Uptake is mediated by apo E .
Hepatic lipase has a dual role: (1) it acts as a ligand to
facilitate remnant uptake and (2) it hydrolyzes
remnant triacylglycerol and phospholipid.
The products released are re utilized for the synthesis
of VLDL.
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Biochemistry for medics
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23. Metabolism of VLDL
There are striking similarities in the mechanisms of
formation of chylomicrons by intestinal cells and of
VLDL by hepatic parenchymal cells
Apart from the mammary gland, the intestine and
liver are the only tissues from which particulate lipid
is secreted.
Newly secreted or "nascent" VLDL contain only a
small amount of apolipoproteins C and E, and the full
complement is acquired from HDL in the circulation
Apo B 100 is essential for VLDL formation.
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Biochemistry for medics
23
24. Metabolism of VLDL
VLDL are secreted into the space of Disse and then into
the hepatic sinusoids through fenestrae in the
endothelial lining. for medics
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24
Biochemistry
25. Catabolism of VLDL
Catabolism of VLDL is similar to chylomicrons
Both phospholipids and apo C-II are required as
cofactors for lipoprotein lipase activity, while apo A-II and
apo C-III act as inhibitors.
Hydrolysis takes place while the VLDLs are attached to
the enzyme on the endothelium.
Triacylglycerol is hydrolyzed progressively through a
diacyl glycerol to a monoacylglycerol and finally to free
fatty acids plus glycerol.
Some of the released free fatty acids return to the
circulation, attached to albumin, but the bulk is
transported into the tissue .
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25
26. Catabolism of VLDL
Reaction with lipoprotein lipase results in the loss of approximately
90% of the triacylglycerol of VLDLs and in the loss of apo C (which
returns to HDL) but not apo E, which is retained.
These changes occurring to VLDL, lead to the formation of VLDL
remnants or IDL (intermediate-density lipoprotein)
After metabolism to IDL, VLDL may be taken up by the liver directly
via the LDL (apo B-100, E) receptor, or it may be converted to LDL.
Only one molecule of apo B-100 is present in each of these lipoprotein
particles, and this is conserved during the transformations.
Thus, each LDL particle is derived from a single precursor VLDL
particle.
In humans, a relatively large proportion of IDL forms LDL, accounting
for the increased concentrations of LDL in humans compared with
many other mammals.
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27. Metabolism of LDL
The liver and many extra hepatic tissues express the LDL
(apo B-100, E) receptor.
It is so designated because it is specific for apo B-100 but
not B-48, which lacks the carboxyl terminal domain of B100 containing the LDL receptor ligand, and it also takes
up lipoproteins rich in apo E.
This receptor is defective in familial
hypercholesterolemia.
Approximately 30% of LDL is degraded in extra-hepatic
tissues and 70% in the liver.
A positive correlation exists between the incidence of
coronary atherosclerosis and the plasma concentration
of LDL cholesterol.
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27
28. Metabolism of VLDL
The liver and many
extrahepatic tissues
express the LDL (apo B100, E) receptor.
It is so designated
because it is specific for
apo B-100
but not B-48, which
lacks the carboxyl
terminal domain of B-100
containing the LDL
receptor ligand,
and it also takes up
lipoproteins rich in apo E.
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Biochemistry for medics
28
29. Metabolism of HDL
Synthesis of HDL
HDL is synthesized and secreted from both liver and
intestine .
However, apo C and apo E are synthesized in the liver
and transferred from liver HDL to intestinal HDL
when the latter enters the plasma.
A major function of HDL is to act as a repository for
the apo C and apo E required in the metabolism of
chylomicrons and VLDL.
Nascent HDL consists of discoid phospholipid bilayer
containing apo A and free cholesterol.
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30. Metabolism of HDL
LCAT and the LCAT activator apo A-I—bind to the
discoidal particles, and the surface phospholipid and
free cholesterol are converted into cholesteryl esters
and lysolecithin .
The nonpolar cholesteryl esters move into the
hydrophobic interior of the bilayer, whereas
lysolecithin is transferred to plasma albumin.
Thus, a nonpolar core is generated, forming a spherical,
pseudomicellar HDL covered by a surface film of polar
lipids and apolipoproteins.
This aids the removal of excess unesterified cholesterol
from lipoproteins and tissues .
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31. Metabolism of HDL
Role of LCAT
LCAT( Lecithin Cholesterol Acyl Transferase) enzyme
catalyzes the esterification of cholesterol to form
Cholesteryl ester. The reaction can be represented as
followsLecithin + Cholesterol
Lysolecithin +
Cholesteryl Ester
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32. Reverse cholesterol transport
The cholesterol
efflux is brought
about by
esterification of
cholesterol under
the effect of LCAT.
The cholesteryl
ester rich HDL
(HDL2) gains entry
through Scavenger
receptor (SR-B1)
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33. Metabolism of HDL
The class B scavenger receptor B1 (SR-B1) has been
identified as an HDL receptor with a dual role in
HDL metabolism.
In the liver and in steroidogenic tissues, it binds HDL
via apo A-I, and cholesteryl ester is selectively
delivered to the cells, although the particle itself,
including apo A-I, is not taken up.
In the tissues, on the other hand, SR-B1 mediates the
acceptance of cholesterol from the cells by HDL,
which then transports it to the liver for excretion via
the bile (either as cholesterol or after conversion to
bile acids) in the process known as reverse
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Biochemistry for medics
cholesterol transport
34. HDL- cycle
HDL3, generated from discoidal HDL by the action of
LCAT, accepts cholesterol from the tissues via the SRB1 and the cholesterol is then esterified by LCAT,
increasing the size of the particles to form the less
dense HDL2.
HDL3 is then reformed, either after selective delivery of
cholesteryl ester to the liver via the SR-B1 or by
hydrolysis of HDL2 phospholipid and triacylglycerol by
hepatic lipase. This interchange of HDL2 and HDL3 is
called the HDL cycle.
Free apo A-I is released by these processes and forms
pre -HDL after associating with a minimum amount of
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35. Metabolism of HDL
A second important mechanism for reverse
cholesterol transport involves the ATP-binding
cassette transporter A1 (ABCA1).
ABCA1 is a member of a family of transporter proteins
that couple the hydrolysis of ATP to the binding of a
substrate, enabling it to be transported across the
membrane.
ABCA1 preferentially transfer cholesterol from cells to
poorly lipidated particles such as pre -HDL or apo A-1,
which are then converted to HDL3 via discoidal HDL
Pre -HDL is the most potent form of HDL inducing
cholesterol efflux from the tissues.
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36. Functions of HDL
Scavenging action- HDL scavenges extra cholesterol
from peripheral tissues by reverse cholesterol
transport
HDL, with the help of apo E competes with LDL for
binding sites on the membranes and prevents
internalization of LDL cholesterol in the smooth cells
of the arterial walls
HDL contributes its apo C and E to nascent VLDL and
chylomicrons for receptor mediated endocytosis
HDL stimulated prostacyclin synthesis by the
endothelial cells, which prevent thrombus formation
HDL also helps in the removal of macrophages from
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Biochemistry
the arterial walls . for medics
37. Summary of formation and fate of
lipoproteins
Chylomicrons is a
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Biochemistry for medics
transporter of
dietary lipids
whereas VLDL is a
transporter of
endogenous
lipids(mainly TGs).
LDL transports
cholesterol to
peripheral cells while
HDL transports
cholesterol from
peripheral cells back
37
to liver.
38. Role of HDL in receptor mediated
endocytosis
HDL contributes its apo C and E to nascent VLDL and
chylomicrons for receptor mediated endocytosis
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39. Clinical Significance of lipoprotein
metabolism
Fatty Liver
is an abnormal accumulation of certain fats
(triglycerides) inside liver cells.
Hepatic triacylglycerol synthesis provides the
immediate stimulus for the formation and secretion
of VLDL.
Impaired VLDL formation or secretion leads to
nonmobilization of lipid components from the liver,
results in fatty liver.
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40. Fatty Liver (contd.)
Fatty livers fall into two main categoriesA)More synthesis of Triglycerides
High carbohydrate diet
High fat feeding
Starvation
Diabetes mellitus
High carbohydrate diet stimulates de novo fatty acid
synthesis by providing excess of Acetyl CoA and high
fat feeding provides more flux of fatty acids from the
diet that can be esterifies to provide excess
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triglycerides.Biochemistry for medics
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41. Fatty Liver (contd.)
B) Defective VLDL synthesis -The second type of fatty liver is
usually due to a metabolic block in the production of plasma
lipoproteins, thus allowing triacylglycerol to accumulate.
The lesion may be due to –
(1)A block in apolipoproteins synthesis
a) Protein energy Malnutrition
b) Impaired absorption
c) Presence of inhibitors of endogenous protein synthesis e.g.Carbon tetra chloride, Puromycin, Ethionine , Heavy metals etc.
d) Hypobetalipoproteinemia- Defective apo B gene can cause
impaired synthesis of apo B protein.
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42. Fatty Liver (contd.)
(2) A failure in provision of phospholipids that are
found in lipoproteins
a)A deficiency of choline, a lipotropic factor can
cause impaired formation of phosphatidyl choline
(Lecithin),a glycerophospholipid.
b)Methionine deficiency can also cause impaired
choline synthesis
c) Inositol deficiency
d)Deficiency of essential fatty acids can also cause
impaired PL synthesis
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Biochemistry for medics
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43. Fatty Liver (contd.)
(3) Impaired Glycosylation- Orotic acid also causes
fatty liver; it interferes with glycosylation of the
lipoprotein, thus inhibiting release, and may also
impair the recruitment of triacylglycerol to the
particles. In conditions of orotic aciduria(disorder of
pyrimidine nucleotide biosynthesis), fatty liver can be
observed.
4) Impaired secretion of VLDL- oxidative stress is a
common cause for membrane disruption of
lipoproteins.
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44. Fatty Liver (contd.)
2) Alcoholic fatty liver
Alcoholism leads to fat accumulation in the liver,
hyperlipidemia, and ultimately cirrhosis.
The fatty liver is caused by a combination of impaired
fatty acid oxidation and increased lipogenesis, which
is thought to be due to changes in the [NADH]/
[NAD+] redox potential in the liver,
and also to interference with the action of
transcription factors regulating the expression of the
enzymes involved in the pathways.
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46. Fatty Liver and Lipotropic agents
Lipotropic agents- Agents such as Choline
Inositol
Methionine and other essential amino acids,
Essential fatty acids,
Anti oxidant vitamins,
Vitamin B12, folic acid and
Synthetic antioxidants which have the apparent
effect of removal of fats from the liver cells, and thus
prevent the formation of fatty liver are called
lipotropic agents. for medics
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Biochemistry
46
47. Primary Disorders of Plasma Lipoproteins
(Dyslipoproteinemias)
Inherited defects in lipoprotein metabolism lead to
the primary condition of either hypo- or
hyperlipoproteinemia .
In addition, diseases such as diabetes mellitus,
hypothyroidism, nephrotic syndrome, and
atherosclerosis are associated with secondary
abnormal lipoprotein patterns that are very similar to
one or another of the primary inherited conditions.
All of the primary conditions are due to a defect at a
stage in lipoprotein formation, transport, or
degradation.
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48. Primary Disorders of Plasma Lipoproteins
(Dyslipoproteinemias)
Name
Defect
Characteristics
Abetalipoproteinemia
No chylomicrons, VLDL,
or LDL are formed
because of defect in the
loading of apo B with
lipid.
Rare; blood acylglycerols
low; intestine and liver
accumulate acylglycerols.
Intestinal malabsorption.
Familial alphalipoprotein deficiency
All have low or near
absence of HDL.
Hypertriacylglycerolemia
due to absence of apo CII, Low LDL levels.
Atherosclerosis in the
elderly.
Hypolipoproteinemias
Tangier disease
Fish-eye disease
Apo-A-I deficiencies
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49. Primary Disorders of Plasma Lipoproteins
(Dyslipoproteinemias)
Name
Defect
Characteristics
Familial lipoprotein
lipase deficiency (type I)
Hypertriacylglycerolemia
due to deficiency of LPL,
abnormal LPL, or apo CII deficiency causing
inactive LPL.
Slow clearance of
chylomicrons and VLDL.
Low levels of LDL and
HDL. No increased risk
of coronary disease.
Familial
hypercholesterolemia
(type II a)
Defective LDL receptors
or mutation in ligand
region of apo B-100.
Elevated LDL levels and
hypercholesterolemia,
resulting in
atherosclerosis and
coronary disease.
Hyperlipoproteinemia
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50. Primary Disorders of Plasma Lipoproteins
(Dyslipoproteinemias)- contd.
Name
Defect
Characteristics
Familial type III
hyperlipoproteinemia
(broad beta disease,
remnant removal disease,
familial
dysbetalipoproteinemia)
Deficiency in remnant
clearance by the liver is
due to abnormality in
apo E.
Increase in chylomicron
and VLDL remnants ,
Causes
hypercholesterolemia,
xanthomas, and
atherosclerosis.
Familial
Hypertriacylglycerolemia
(type IV)
Overproduction of VLDL
often associated with
glucose intolerance and
hyperinsulinemia.
High cholesterol, VLDL,
Subnormal LDL and
HDL. Associated with
Alcoholism, diabetes
mellitus and obesity.
Hepatic lipase deficiency
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Deficiency of the enzyme Patients have xanthomas
leads to accumulation of and coronary heart
large triacylglycerol-rich disease.
HDL and VLDL remnants
50
Biochemistry for medics
51. Atherosclerosis
Read the details at
http://www.namrata.co/atherosclerosis-a-review-power-poin
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51
52. For further details
Refer
A Case Oriented Approach Towards Biochemistry
by: Namrata Chhabra, Sahil Chhabra
http://www.jaypeedigital.com/BookDetails.aspx?id=9789350
And visit our web sitehttp://www.namrata.co/category/metabolism-lipids/subject
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