l i p i d s ii
DESCRIPTION
L I P I D S II. Simple Lipids. Neutral fats and oils Monoacyl glycerols (monoglycerides) Diacyl glycerols (diglycerides) Triacyl glycerols (triglycerides) Triglycerides found in seeds and animal adipose tissue Triacyl glycerols (triglycerides) Lipid storage form - PowerPoint PPT PresentationTRANSCRIPT
L I P I D S IIL I P I D S II
Simple Lipids Neutral fats and oils
Monoacyl glycerols (monoglycerides) Diacyl glycerols (diglycerides) Triacyl glycerols (triglycerides)
Triglycerides found in seeds and animal adipose tissue
Triacyl glycerols (triglycerides) Lipid storage form
Where in the body? Adipocytes!! Most lipids consumed are triglycerides
I- Triglycerides Most common structure in dietary lipids Composed of one glycerol molecule and three fatty acids connected
by an ester bond (bond between an alcohol and and organic acid) Fatty acids may be same or mixed
Glycerol
Fatty Acid
Fatty Acid
Fatty Acid
Triacyl glycerol (triglyceride)
II- WaxesII- WaxesWaxes are also esters like fats Use one alcohol instead of glycerolEsters of:
– Long-chain fatty acid– Long-chain alcohol
The longer the chains, the higher the melting pointProtects the skin of plants and fur of animals Examples of waxes include:
– Carnuba, from Brasilian wax palm – Beeswax
Complex Lipids -Phospholipids Two primary types:
Glycerophosphatides Backbone structure is glycerol Part of cell membranes, chylomicrons,
lipoproteins Sphingophosphatides
Backbone structure is sphingosine Part of sphingomyelin
GlycerophospholipidsGlycerophospholipids (phosphoglycerides), are common constituents of cellular membranes.They have a glycerol backbone.Hydroxyls at C1 & C2 are esterified to fatty acids.The C3 hydroxyl is esterified to Pi
O P O
O
O
H2C
CH
H2C
OCR1
O O C
O
R2
X
glycerophospholipid
In most glycerophospholipids (phosphoglycerides), Pi is in turn esterified to OH of a polar head group (X): e.g., serine, choline, ethanolamine, glycerol, or inositol.
The 2 fatty acids tend to be non-identical. They may differ in length and/or the presence/absence of double bonds.
Glycerophospholipids
With inositol as polar head group, is one glycerophospholipid. In addition to being a membrane lipid, phosphatidylinositol has roles in cell signaling.
O P
O
O
H2C
CH
H2C
OCR1
O O C
O
R2
OH
H
OH
H
H
OHH
OH
H
O
H OH
phosphatidyl- inositol
Phosphatidylinositol:
Phosphatidylcholine (Lecithin):With choline as polar head group. It is a common membrane lipid.
O P O
O
O
H 2 C
C H
H 2 C
OCR 1
O O C
O
R 2
C H 2 C H 2 N C H 3
C H 3
C H 3
+
p h o sp h a tid y lch o lin e
O P O
O
O
H2C
CH
H2C
OCR1
O O C
O
R2
X
glycerophospholipid
Each glycerophospholipidincludes a polar region:
glycerol, carbonyl O of fatty acids, Pi, & the polar head group (X)
non-polar hydrocarbon tails of fatty acids (R1, R2).
Phospholipids … Significant use in feed industry as
emulsifiers Lipids form emulsion in water
Phospholipid sources: Liver, egg yolk, Soybeans, wheat germ Peanuts
H2CHC
OH
CH
N+ CH
C
CH2
CH3
H
H3
OH
( )12
sphingosine
are derivatives of the lipid sphingosine, which has a long hydrocarbon tail, and a polar domain that includes an amino group.The amino group of sphingosine can form an amide bond with a fatty acid carboxyl, to yield a ceramide.In the more complex sphingolipids, a polar “head group" is esterified to the terminal hydroxyl of the sphingosine moiety of the ceramide.
Sphingolipids:
H2CHC
OH
CH
NH CH
C
CH2
CH3
H
OH
( )12
C
R
O
ceramide
Sphingomyelin, with a phosphocholine head group, is similar in size and shape to the glycerophospholipid phosphatidyl choline.
Sphingomyelin has a phosphocholine or phosphethanolamine head group.
Sphingomyelins are common constituent of plasma membranes
H2CHC
O
CH
NH CH
C
CH2
CH3
H
OH
( )12
C
R
O
PO O
OH2C
H2CN+
CH3
H3C
CH3
Sphingomyelin
phosphocholine
sphingosine
fatty acid
Complex Lipids - Glycolipids Carbohydrate component in structure Cerebrosides & gangliosides
Medullary sheaths of nerves; white matter of brain
Cerebrosides and gangliosides, collectively called glycosphingolipids, are commonly found in the outer leaflet of the plasma membrane bilayer.
cerebroside with -galactose head group
H2CHC CH
NH CH
C
CH2
CH3
OH
C
R
O
OH O
H H
H
OHH
OH
CH2OH
HO
H
( )12
A cerebroside is a sphingolipid (ceramide) with a monosaccharide such as glucose or galactose as polar head group.A ganglioside is a ceramide with a polar head group that is a complex oligosaccharide, including the acidic sugar derivative sialic acid.
Disease Symptom Sph. Lip Enzyme
Tay-Sachs Blindness,muscles weak
Ganglioside
GM2
-hexose-aminidase A
Gaucher’s Liver & spleen enlarge, MR
Gluco-cerebroside
-glucosidase
Krabbe’s demyelation,MR
Galacto-cerebroside
-galactosidase
Nieman-Pick
MR Sphingomyelin
Sphingomyelinase
Sphingolipid Storage Diseases
C
H2C O
O
H2C O P
O
OH
O
C
O
R1
C
O
R2
CH2 C
OH
H
CH2 O P O
OH
O
CH2
C OH
CH2O
C
O
R3
C
O
R4
H
glycerolglycerol
glycerol
A polyglycerol phospholipid; makes up 15% of total lipid-phosphorus content of the myocardium – associated with the cell membraneCardiolipids are antigenic and as such are used in serologic test for syphilis (Wasserman test).
CH
HC
H2C
CH=CH(CH 2)12CH3
N H
HO
Storage (neutral) Membrane (polar)
G SFAP
H2C
HC
H2C
(CH2)14CH3
(CH2)7CH=CH(CH 2)7CH3
(CH2)16CH3
OC
OC
OC
O
O
O
FA
FA
P A C MS/OS
FA
TAG
PL GL
GPL SL SL
TAG: triacylglycerol PL: phospholipids GPL: glycerophospholipidG: glycerolFA: fatty acid P: phosphate A: alcohol SL: sphingolipidC: choline GL: glycolipid S: sphingosineMS/OS: monosaccharide/oligosaccharide
ABDULLATIF TAHA ABDULLAABDULLATIF TAHA ABDULLADep. Of BIOCHEMISTRYDep. Of BIOCHEMISTRY