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 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

Triacyl glycerol (triglyceride)

II- Waxes Waxes are also esters like fats Use one alcohol instead of glycerol Esters of: – Long-chain fatty acid – Long-chain alcohol The longer the chains, the higher the melting point Protects 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

Glycerophospholipids Glycerophospholipids (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 P i

In most glycerophospholipids (phosphoglycerides), P i 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. Phosphatidylinositol:

Phosphatidylcholine (Lecithin):  With choline as polar head group.  It is a common membrane lipid.

Each glycerophospholipid includes  a polar region: glycerol, carbonyl O of fatty acids, P i, & the polar head group ( X )  non-polar hydrocarbon tails of fatty acids (R 1, R 2 ).

Phospholipids … Significant use in feed industry as emulsifiers Lipids form emulsion in water Phospholipid sources: Liver, egg yolk, Soybeans, wheat germ Peanuts

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:

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

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. 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.

DiseaseSymptomSph. LipEnzyme Tay-SachsBlindness, muscles weak Ganglioside GM 2  -hexose- aminidase A Gaucher’sLiver & spleen enlarge, MR Gluco- cerebroside  -glucosidase Krabbe’sdemyelation, MR Galacto- cerebroside  - galactosidase Nieman- Pick MR Sphingomyeli n Sphingomyelina se Sphingolipid Storage Diseases

Cardiolipids A polyglycerol phospholipid; makes up 15% of total lipid-phosphorus content of the myocardium – associated with the cell membrane Cardiolipids are antigenic and as such are used in serologic test for syphilis (Wasserman test).

Storage (neutral)Membrane (polar) G S FA P PACMS/OS FA TAG PLGL GPLSL TAG: triacylglycerolPL: phospholipidsGPL: glycerophospholipid G: glycerol FA: fatty acidP: phosphateA: alcoholSL: sphingolipid C: cholineGL: glycolipidS: sphingosine MS/OS: monosaccharide/oligosaccharide

ABDULLATIF TAHA ABDULLA Dep. Of BIOCHEMISTRY