1. Triglyceride and phospholipid synthesis and degradation

2. Theoreticcally ester bond is formed
by the withrawal of H2O, but in the
body FA-CoA is necessary, that
contains high group transfer potential
thioester bond and enzymes.
The more the cis configuration FA and the more double bond is found in FA, the less London-forces are possible
between fatty acids, so the lipid is
more fluid, the stiffening point is higher.
Compare pig fat and sunflower oil.

3. Characteristics and function of triacylglycerides
hydrofobic neutral fats
most efficient food stores, because:
many H-atoms of FAs can burn in oxidative phosphorylation to water coupled to the formation of many ATP
on the contrary: glucose is partially oxidized in glycogen
as hydrofobic molecules, they interact with each other in small place, but not with water, compared to glycogen that absobs many water, forms gel
heat insulators: animals that sleep in winter or live in cold water or near to poles bear thick fat layer under their skin
mechanical protection is given to organs during movement, strike

4. Phospholipids are amphipathic molecules: hydrophilic and hydrophobic parts are
separated.

5. Phospholipids form lipid bilayer in every membrane in the cells, hydrophilic head orients toward the water phase.
In the membranes cholesterol, peripheral and integral proteins are found.
Glycosylated lipids and proteins are in the outer leaflet.
signal transduction
moleculeas are
liberated from
membranes:
IP3, DAG, PGE2, PGI2,
TXA2, HETE, PAF

6. Monolayer phospholipids
Hydrophobic triglycerides and cholesterol esters are packed in monolayer phospholipids and proteins in the blood and lymph. The non
stoichiometric aggregate is called
lipoprotein.
mixed micell formed during lipid digestion in gut
simple micell

7. Phospholipases 1st acyl group is cut by PLA1 or PLB after PLA2
= saturated
= unsaturated
2nd acyl group is cut
by PLA2
or LCAT in blood
PLC can be specific for phosphatidyl inositol
signal transduction

8. Common steps in triacylglyceride and
phosholipid synthesis
in liver

9. From
Phosphatidic acid (in middle)
the synthesis of
tiglyceride (on the botton)
and two kind of phospholipid:
phosphatidyletanolamine
and phosphatidylcholine
(on sides and bellow)

10. Synthesis of triglycerides in the enterocytes
proceeds with alternative mechanism:
does not need phosphatidic acid, nor glycerol, nor
glcolysis intermedier, just monoglyceride and FA
derived from food lipids are enough.
chylomicron
lipoprotein
lymphatic system
blood
phospholipids + proteins

11. phosphatidyiletanolamine and phosphatidylserine interconversion
Phosphatidylcholine,
phosphatidyiletanolamine
and phosphatidylserine
interconversion
―N+―(CH3)3
foszfatidylcholine
> 3 SAH
methyltransferase LIVER
3 SAM
liver

12. Phosphatidylinositol and cardiolipin
synthesis
phosphatidylinositol-
trisphosphate = PIP3
DAG
inositol-trisphosphate
=IP3
signal transduction

14. = regulation of lipolysis in adipocyte
adrenal
cortex
tissues
liver
MAG-lipáz

15. Triglyceride digesting enzymes
each hydrolyses ester bond
the acitive site of some lipases equals to serine proteases’ active centre: Ser, His, Asp,
a Ser OH attacks ester bond carbonyl C-atom
enzyme name source place of effect substrate product
lingual lipase salivary gland stomach milk fat 1,2-DAG+ FA
gastric lipase stomach stomach milk fat 1,2-DAG + FA
pancreas lipase pancreas small intestine each TAG 2-MAG +2 FA
+ colipase
non specific lipase+ pancreas small intestine many lipids e.g. glycerol + FA
bile acids MAG
hormonsensitive lipase cells cells each TAG 2-MAG + 2FA
MAG-lipase cells cells 2-MAG glycerol + FA
hepatic lipase hepatocyte liver sinusoids lipoprot. TAG 2-MAG + 2 FA
lipoprotein lipase parenchymal cell blood lipoprot. TAG 2-MAG + 2FA
+ apoprot. C2

18. From Ceramide
synthesis of
cerebroside, sphingomyelin
and gangliozids