lipid - universitas brawijayablog.ub.ac.id/virgus/files/2013/06/01_lemak.pdf · lipid functions 1....

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LIPIDINTRODUCTION:4 types of macromolecules in cellular biology

1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids

The most common elements found in living organisms include:– Carbon (C)– Oxygen (O)– Nitrogen (N)– Hydrogen (H)– Phosphorus (P)– Sulfur (S)

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Lipid Characteristics• Hydrophobic Insoluble in water, soluble in

organic solvents (alcohols, acetone, chloroform)• Lipid lebih kecil jika dibandingkan dengan

makromolekul yang lain• Lipid sebagian besar terdiri atas gugus non polar

hydrocarbon (CH3, CH2, dan CH)• Disusun dari molekul 3 fatty acid dan Glycerol

neutral fat (Lipid)• Fat & Oil that are liquid at room temperature

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Lipid Characteristics

• Hydrophobic

• Ratio of H to O is much greater than 2:1For example…

C18H34O3

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Lipid Structure• 2 monomers

Glycerol Fatty acid

Hydrocarbon chains

C55H102O6

More bonds means more Energy!

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Fatty acids - Lipids• Are monocarboxylic acid contains even number C atoms

• Two types: saturated (C-C sb) and unsaturated (C-C db)

• Fatty acids are components of several lipid molecules.

• E,g. of lipids are triacylglycerol, steroids (cholestrol, sex hormones), fat soluble vitamins.

Functions• Storage of energy in the form of fat• Membrane structures• Insulation (thermal blanket)• Synthesis of hormones

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Fatty acids: carboxylic acid + long hydrocarbon chain

CO

OHCH3

Carboxylic acid

Hydrocarbon chain

A saturated fatty acid

An unsaturated fatty acid

C

O

OH

CH3

© 2007 Paul Billiet ODWS

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Saturated fatty acids Unsaturated fatty acids

no double bonds one or more double bonds

abundant in fats abundant in oils

more reduced less reduced

more energy less energy

high melting point low melting point


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Lipid Characteristics & Function

• 4 types: – 1-triglycerides (fats & oils)

• (long-term energy storage, insulation)

– 2-phospholipids (primary component of cell membrane)

– 3-steroids (cell signaling)• cholesterol molecules modified to form sex hormones.

(e.g. testosterone, estrogen, etc.)

– 4-waxes (protection, prevents water loss)• Used mainly by plants, but also bees, some furry

animals and humans.

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Fats and Oilsfatty acids + glycerol (1, 2 or 3 = mono , di or triglycerides)

C

O

OH

CH

3

C

O

OHCH

3

HO – CH2

HO - CH2

HO - CH Condensation reactions


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Two fatty acids joining glycerol = A diglyceride

C

O

CH3

C

O

CH3

O - CH3

HO - CH3

O - CH

+ 2H20


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Triglyceride

Glycerol Fatty Acid Chains

The shape of Triglyceride is like the letter E

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Triglycerides

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Oils• Oils occur in all parts of a plant, but are most

common in seeds. Some seeds have so much oil that it can be commercially harvested. The most commonly used oils are cotton, sesame, safflower, sunflower, olive, coconut, peanut, corn, castor bean, and soybean oils.

• The most common seed oil fatty acids are oleic acid (one double bond), linoleic acid (two double bonds), and linolenic acid (three double bonds). Linoleic and linolenic are essential fatty acids – we can’t make them ourselves.

Olive Oil

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Phospholipids

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Phospholipids

• in lipoprotein membranes (plasma, nuclear, mitochondrial etc.) Komponen utama membran sel


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Other lipidsSteroids: multiple ring structures (e.g. cholesterol)

• Functions: cell membrane structure, digestion (help to emulsify fats), hormones (testosterone etc), vitamins (e.g. Vitamin D), poisons

Waxes: long chain alcohol + fatty acids

• Water proof coating to leaves, fur feathers, insect exoskeletons.

• Used by bees to construct their honey combs.


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Steroids

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Waxes• Waxes are complex mixtures of fatty

acids linked to long-chain alcohols. Waxes comprise the outermost layer of leaves, fruits, and herbaceous stems and are called EPICUTICULAR waxes. Waxes embedded in the cuticle of the plant are cuticular waxes. Cutin is another wax in the cuticle and it makes up most of the cuticle. Suberin is a similar wax that is found in cork cells in bark and in plant roots. Both help prevent water loss by the plant.

• Structures of waxes vary depending on which plant produced them.

• Waxes are usually harder and more water repellant than other fats.

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Bayberry Wax

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Jojoba Wax

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LIPID FUNCTIONS IN GENERAL• STRUCTURAL: biological membranes

(phospholipids, steroids, glycolipids), cushioning (fat deposits round the kidneys)

• ELECTRICAL INSULATION: myelin sheath round axons

• THERMAL INSULATION: subcutaneous fat deposits mengatur suhu tubuh

• WATER PROOFING: waxes and oils• ENERGY STORE AND SUBSTRATE:

very condensed form of energy (37 kJ g-1) used by animals and seeds.

• HORMONES: steroids• VITAMINS: precursor to Vit D• BUOYANCY: oil droplets in plankton

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Lipid Functions

1. Surround and contain aqueous cell contents (plasma membranes)

2. Chemical signals from cell to cell (hormones and steroids)

3. Energy storage (fats)

4. Cushion and protect internal organs

5. Insulate body (subcutaneous fat)

6. Lubricate skin and hair, prevent cracking (oils)

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Lipid Functions: Surround and contain aqueous cell contents (plasma membranes)

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Lipid Functions: Hormones and SteroidsChemical messengers

• 4 fused ring structure

• Hydrophobic

• Estrogen & testosterone are sex hormones, they act as chemical signals

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Lipid Functions: Hormones and Steroids

• Cholesterol is a steroid. It is essential to healthy cell membranes

• Also, other steroids are made from cholesterol

• But cholesterol cardiovascular disease !!

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Fatty acids have four major biological roles:

1. They are components of membranes (glycerophospholipids and sphingolipids);

2. Several proteins are covalently modified by fatty acids;

3. They act as energy stores (triacylglycerols) and fuel molecules;

4. Fatty acid derivatives serve as hormones and intracellular second messengers.

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Fatty AcidsFatty acids can be classified either as:

– saturated or unsaturated

– according to chain length:

• short chain FA: 2-4 carbon atoms

• medium chain FA: 6 –10 carbon atoms

• long chain FA: 12 – 26 carbon atoms

• essential fatty acids vs those that can be biosynthesized in the body:

– linoleic and linolenic are two examples of essential fatty acid

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Unsaturated fatty acids

• Monoenoic acid (monounsaturated)

H3C

HOOC

Double bond is alwayscis in natural fatty acids.This lowers the meltingpoint due to “kink” inthe chain

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• Dienoic acid: linoleic acid

(CH 2)4CH 3 CH=CH CH 2 CH=CH (CH 2)7 COOH

cis

linoleic acid

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Unsaturated fatty acids• Various conventions are in use for indicating the

number and position of the double bond(s)

HC CH( CH 2 ) 7 COOH( CH 2 ) 7H 3 C

191 8

1 0

1 8 : 1 , 9 o r 9 1 8 : 1

H 3C CH 2CH 2CH 2CH 2CH 2CH 2CH 2CH CH( CH 2)7COOH

191017n

2 3 4 5 6 7 8 9 10 18

9, C 18:1 or n-9, 18:1

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• Polyenoic acid (polyunsaturated)

COOH

CH3

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• Monoenoic acids (one double bond):• 16:1, 9 7: palmitoleic acid (cis-9-hexadecenoic

acid

• 18:1, 9 9: oleic acid (cis-9-octadecenoic acid)

• 18:1, 9 9: elaidic acid (trans-9-octadecenoic acid)

• 22:1, 13 9: erucic acid (cis-13-docosenoic acid)

• 24:1, 15 9: nervonic acid (cis-15-tetracosenoic acid)

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• Trienoic acids (3 double bonds)• 18:3;6,9,12 6 : -linolenic acid (all cis-6,9,12-

octadecatrienoic acid)

• 18:3; 9,12,15 3 : -linolenic acid (all-cis-9,12,15-octadecatrienoic acid)

• Tetraenoic acids (4 double bonds)• 20:4; 5,8,11,14 6: arachidonic acid (all-cis-

5,8,11,14-eicosatetraenoic acid)

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• Pentaenoic acid (5 double bonds)• 20:5; 5,8,11,14,17 3: timnodonic acid or

EPA (all-cis-5,8,11,14,17-eicosapentaenoic acid)*

• Hexaenoic acid (6 double bonds)• 22:6; 4,7,10,13,16,19 3: cervonic acid or

DHA (all-cis-4,7,10,13,16,19-docosahexaenoic acid)*

Both FAs are found in cold water fish oils

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Typical fish oil supplements

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Properties of fats and oils

• fats are solids or semi solids• oils are liquids• melting points and boiling points are not usually

sharp (most fats/oils are mixtures)• when shaken with water, oils tend to emulsify• pure fats and oils are colorless and odorless

(color and odor is always a result of contaminants) – i.e. butter (bacteria give flavor, carotene gives color)

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Examples of oils

• Olive oil – from Oleo europa (olive tree)• Corn oil – from Zea mays• Peanut oil – from Arachis hypogaea• Cottonseed oil – from Gossypium• Sesame oil – from Sesamum indicum• Linseed oil – from Linum usitatissimum• Sunflower seed oil – from Helianthus annuus• Rapeseed oil – from Brassica rapa• Coconut oil – from Cocos nucifera

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Non-drying, semi-drying and drying oils

• based on the ease of autoxidation and polymerization of oils (important in paints and varnishes)

• the more unsaturation in the oil, the more likely the “drying” process– Non-drying oils:

• Castor, olive, peanut, rapeseed oils

– Semi-drying oils• Corn, sesame, cottonseed oils

– Drying oils• Soybean, sunflower, hemp, linseed, tung, oiticica oils

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Fatty acid reactions• salt formation

• ester formation

• lipid peroxidation

RCO 2H RCO 2-Na +NaOH

(a soap)

R'OH + RCO 2 H RCO 2 R'-H 2 0

R

R'

H H

R R'

OOH

O2

non-enzymatic

very reactive

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SoapsProcess of formation is known as saponification

Types of soaps:

• Sodium soap – ordinary hard soap

• Potassium soap – soft soap (shaving soaps are potassium soaps of coconut and palm oils)

• Castile soap – sodium soap of olive oil

• Green soap – mixture of sodium and potassium linseed oil

• Transparent soap – contains sucrose

• Floating soap – contains air

• Calcium and magnesium soaps are very poorly water soluble (hard water contains calcium and magnesium salts –these insolubilize soaps)

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Lipid peroxidation

• a non-enzymatic reaction catalyzed by oxygen

• may occur in tissues or in foods (spoilage)– the hydroperoxide formed is very reactive

and leads to the formation of free radicals which oxidize protein and/or DNA (causes aging and cancer)

• principle is also used in drying oils (linseed, tung, walnut) to form hard films

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Hydrogenated fats

• hydrogenation leads to either saturated fats and or trans fatty acids

• the purpose of hydrogenation is to make the oil/fat more stable to oxygen and temperature variation (increase shelf life)

• example of hydrogenated fats: Crisco, margarine

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Neutral lipids

• Glycerides (fats and oils) ;glycerides– Glycerol

– Ester of glycerol - mono glycerides, diglycerides and triglycerides

• Waxes – simple esters of long chain alcohols

CH2OH

CH2OH

OHH OH

OH

OH

glycerol is a prochiral molecule

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GLYCERIDES

O

OH

OH

R

O

O

OH

O

R

O

R

O

O

O

R

O

R

O

OR

O

MONOGLYCERIDE DIGLYCERIDE TRIGLYCERIDE

Function: storage of energy in compact form and cushioning

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Stereospecific numbering

• carbon 2 of triglycerides is frequently asymmetric since C-1 and C-3 may be substituted with different acyl groups

• by convention we normally draw the hydroxyl group at C-2 to the left and use the designation of sn2 for that particular substituent

• C-1 and C-3 of the glycerol molecule become sn1 and sn3 respectively

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Analytical methods to evaluate lipids:

• saponification number

• iodine value (Hanus method)

• free fatty acids

• acetyl number

• Reichert-Meissl number

• HPLC/GC (for more precise analysis)

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Saponification number

• gives some clue as to the average size of fatty acids in a given sample of fat

• defined as the number of milligrams of KOH needed to neutralize the fatty acids in 1 Gm of fat

• butter (large proportion of short chain FAs) sap. no. 220 – 230

• oleomargarine (long chain FAs) sap. No is 195 or less

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Iodine number

• measures the degree of unsaturation in a given amount of fat or oil

• the iodine number is the number of grams of iodine absorbed by 100 grams of fat

• Cottonseed oil: 103 –111• Olive oil: 79 – 88• Linseed oil: 175 –202

• frequently used to determine adulteration of commercial lots of oils

HHI I

HHI2

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Acetyl number• some fatty acids have hydroxyl groups

(CH2)21H3C CH

OH

COOH

cerebronic acid

(CH2)5H3C CH CH2

OH

CH CH (CH2)7 COOH

ricinoleic acid

The acetyl number gives the proportion of these hydroxyl-containing fattyacids in a given sample of fat or oil

fatty acid

OH

acetic anhydridefatty acid

O C

O

CH3

fatty acid

OH

+

COOHH3C

titrate with standardizedKOH

acetylated fatty acid

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Acetyl number

• the acetyl number is the number of milligrams of KOH needed to neutralize the acetic acid of 1 Gm of acetylated fat– examples:

• castor oil – 146 –150• cod liver oil – 1.1• cottonseed oil – 21 – 25• olive oil – 10.5• peanut oil – 3.5

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Reichert – Meissl number

• measures the amount of volatile fatty acids (low MW and water soluble Fas)

• the R-M number is the number of milliliters of 0.1N alkali required to neutralize the soluble fatty acids distilled from 5 Gm of fat

• butter fat has a high R-M number

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WAXES• simple esters of fatty acids (usually saturated with

long chain monohydric alcohols)

H 3 C (CH 2 ) 14 C

O

O CH 2 (CH 2 ) 28 -CH 3

lo n g c h a in a lc o h o l

f a t t y a c id

Beeswax – also includes some free alcohol and fatty acidsSpermaceti – contains cetyl palmitate (from whale oil) –useful forPharmaceuticals (creams/ointments; tableting and granulation)Carnauba wax – from a palm tree from brazil – a hard wax used on cars and boats

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Bee’s wax

Spermaceti source

Carnauba wax source

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Waxes

(CH2)14H3C CH2-OH cetyl alcohol

(CH2)24H3C CH2-OH hexacosanol

(CH2)28H3C CH2-OH triacontanol (myricyl alcohol)

Examples of long chain monohydric alcohols found in waxes

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Phospholipids• the major components of cell membranes

– phosphoglycerides

O R

O R'

O

P

O

O

O

O-

X

Ofatty acids (hydrophobic tail)

glycerol

phosphate

Phospholipids are generally composed of FAs, a nitrogenous base, phosphoricacid and either glycerol, inositol or sphingosine

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O R

O R'

O

P

O

O

O

O-

X

Of a t t y a c i d s ( h y d r o p h o b i c t a i l )

g l y c e r o l

p h o s p h a t e

X = H (phosphatidicacid)-precursortootherphospholipids

X = CH2-CH2-N+(CH3)3 phosphatidyl choline

X = CH2-CH(COO-)NH3+ phosphatidyl serine

X = CH2-CH2-NH3+ phosphatidyl ethanolamine

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Phosphatidyl inositol

Commonly utilized in cellular signaling

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Sphingolipids

OH

NH2

OH

NH2

OH

HO R long chain hydrocarbon

attach fatty acid here

attach polar head group here

sphingosine

Based on sphingosine instead of glycerol

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Sphingomyelin (a ceramide)

NH

O

HO R

PO

O-

O

N(CH3)+

R'

O

usually palmitic acid

phosphatidyl choline (also can be ethano

It is a ubiquitous component of animal cell membranes, where it is by far the most abundant sphingolipid. It can comprise as much as 50% of the lipids in certain tissues, though it is usually lower in concentration than phosphatidylcholine

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Ether glycerophospholipids• Possess an ether linkage instead of an

acyl group at the C-1 position of glycerol– PAF ( platelet activating factor)

– A potent mediator in inflammation, allergic response and in shock (also responsible for asthma-like symptom

– The ether linkage is stable in either acid or base

– Plasmalogens: cis ,-unsaturated ethers

– The alpha/beta unsaturated ether can be hydrolyzed more easily

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Ether glycerophospholipids

H 2C CH

O

CH 2

O

O

P

O

-O O

C O

CH 3

CH 2 CH 2 N

CH 3

CH 3

CH 3

platele t activating factor or P A F

H 2C CH

O

CH 2

O

O

P

O

-O O

C O

CH 2 CH 2 N

CH 3

CH 3

CH 3

A choline p lasm alogen

H

H

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glycolipids

NH

O

HO R

R'

O

SUGAR polar head is a sugar

beta linkage

There are different types of glycolipids: cerebrosides, gangliosides,lactosylceramides

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GLYCOLIPIDS• Cerebrosides

• One sugar molecule– Galactocerebroside – in neuronal membranes– Glucocerebrosides – elsewhere in the body

• Sulfatides or sulfogalactocerebrosides• A sulfuric acid ester of galactocerebroside

• Globosides: ceramide oligosaccharides• Lactosylceramide

– 2 sugars ( eg. lactose)

• Gangliosides• Have a more complex oligosaccharide attached• Biological functions: cell-cell recognition; receptors for

hormones

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Gangliosides

• complex glycosphingolipids that consist of a ceramide backbone with 3 or more sugars esterified,one of these being a sialic acid such as N-acetylneuraminic acid

• common gangliosides: GM1, GM2, GM3, GD1a, GD1b, GT1a, GT1b, Gq1b

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Ganglioside nomenclature

• letter G refers to the name ganglioside• the subscripts M, D, T and Q indicate mono-, di-,

tri, and quatra(tetra)-sialic-containing gangliosides

• the numerical subscripts 1, 2, and 3 designate the carbohydrate sequence attached to ceramide

• Numerical subscripts:• 1. Gal-GalNAc-Gal-Glc-ceramide• 2. GalNAc-Gal-Glc-ceramide• 3. Gal-Glc-ceramide

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O

CH2OH

H OH

H

OH

OH

O

O

CH2OH

H NH

H

OH

O

CH2OH

H OH

H

H

O

CH2OH

H OH

H

H

OH H

O

H

O

O

CH2HC

HC

NH

C O

R

HO

C

C

O

O

C O

CH3

NH

H

CHOH

CHOH

OH

CH2OH

H

H

COO-C

O

H3C

H

H

H

H

D-Galactose

N-Acetyl-D-galactosamine D-galactose D-glucose

N-acetylneuraminidate (sialic acid)

A ganglioside (GM1)

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Cardiolipids

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-phosphoruscontent of the myocardium – associated with the cell membrane

Cardiolipids are antigenic and as such are used in serologic test forsyphilis (Wasserman test)

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Sulfolipids

• also called sulfatides or cerebroside sulfates

• contained in brain lipids

• sulfate esters of cerebrosides

• present in low levels in liver, lung, kidney, spleen, skeletal muscle and heart

• function is not established

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Lipid storage diseases• also known as sphingolipidoses• genetically acquired• due to the deficiency or absence of a catabolic

enzyme• examples:

• Tay Sachs disease• Gaucher’s disease• Niemann-Pick disease• Fabry’s disease

• http://www.ninds.nih.gov/disorders/lipid_storage_diseases/lipid_storage_diseases.htm

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Genetic defects in ganglioside metabolism

• leads to a buildup of gangliosides (ganglioside GM2) in nerve cells, killing them

NAcGal Gal Gal Glu

NAcNeu

enzyme that hydrolyzes here (beta hexosaminodase)is absent in Tay-Sachs disease

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Tay-Sachs disease

• a fatal disease which is due to the deficiency of hexosaminidase A activity

• accumulation of ganglioside GM2 in the brain of infants

• mental retardation, blindness, inability to swallow• a “cherry red “ spot develops on the macula (back

of the the eyes)• Tay-Sachs children usually die by age 5 and often

sooner

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Genetic defects in globoside metabolism

• Fabry’s disease:• Accumulation of ceramide trihexoside in kidneys of

patients who are deficient in lysosomal -galactosidase A sometimes referred to as ceramide trihexosidase

• Skin rash, kidney failure, pains in the lower extremities

• Now treated with enzyme replacement therapy: agalsidase beta (Fabrazyme)

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Genetic defects in cerebroside metabolism

• Krabbe’s disease: • Also known as globoid leukodystrophy• Increased amount of galactocerebroside in the white matter of

the brain• Caused by a deficiency in the lysosomal enzyme

galactocerebrosidase• Gaucher’s disease:

• Caused by a deficiency of lysosomal glucocerebrosidase• Increase content of glucocerebroside in the spleen and liver• Erosion of long bones and pelvis• Enzyme replacement therapy is available for the Type I

disease (Imiglucerase or Cerezyme)• Also miglustat (Zavesca) – an oral drug which inhibits the

enzyme glucosylceramide synthase, an essential enzyme for the synthesis of most glycosphingolipids

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Miglustat (Zavesca)

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Steroids

•The carbon skeleton of steroids is bent to form 4 fused rings

Cholesterol is the “base steroid” from which your body produces other steroidsEstrogen & testosterone are also steroids

Cholesterol

TestosteroneEstrogen

Synthetic Anabolic Steroids are variants of testosterone

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Steroids

HCH3

HH

CH3

H

• The features common to the ring system of most naturally occurring steroids are illustrated here

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Androgens• Androgens: male sex hormones

– synthesized in the testes

– responsible for the development of male secondary sex characteristics

AndrosteroneTestosteroneO

HOH

H

H3 C H

H

H3 C H3 C

H

HH3 C

H

O

HO

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Estrogens• Estrogens: female sex hormones

– synthesized in the ovaries

– responsible for the development of female secondary sex characteristics and control of the menstrual cycle

Progesterone Estradiol

H 3 C

H

HH 3 C

H

C = OH

O

C H 3

O H

H O

H

H

H

H 3 C

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Sterols• Sterol

– Four fused rings

• Greater rigidity than other membrane lipids

– One or more hydroxyl groups

• Gives amphipathic character

– Hydrocarbon side chain

• Length of C16 FA

• Cholesterol

– Most abundant sterol in animals

– Produced by liver; supplied by diet

– High levels lead to gallstones and deposits on arteries (plaque)

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Sterols

• Metabolic precursors of steroid hormones– Regulate physiological

functions

– Androgens (testosterone)

– Estrogens (-estradiol)

– Glucocorticoids (cortisol)

• Insoluble in water

• Bind to proteins for transport to target tissue

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Other Lipids• Classified on basis of physical

properties– Solubility

– Hydrophobicity

– Amphiphilicity

• Fat-soluble vitamins– Vitamins A, E, K (and D)

– Isoprenoids

• Eicosanoids– Prostaglandins

– Thromboxanes

– Leukotrienes

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Vitamin D• Sterol derivatives

– Open B rings

• Function– Regulate Ca and P absorption

during bone growth

• Sources– Diet: D2 (milk additive, plant

sources) and D3 (animal sources)

– Precursor: intermediate in cholesterol synthesis

– Formed in skin non-enzymatically from 7-dehydrocholesterol

• Deficiency– Soft bones, impaired growth and

skeletal deformities in children

Inactive form

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Vitamin A

• Collective term for retinol, retinal, retinoic acid

• Formed from oxidative cleavage of -carotene in liver

• Function– Aldehyde: visual cycle/process, component of

rhodopsin (visual pigment)

– Alcohol, carb acid: growth, reproduction

• Deficiency– Night blindness

– Xerophthalmia• Dryness in eyes

• No tear production

• Damage to cornea

• Leads to blindness

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Vitamin K• Phylloquinone or menaquinone• Function

– Synthesis of blood clotting proteins• Sources

– K1 = plants; K2 = animals– Bacteria in intestine

• Deficiency– Unlikely due to synthesis and wide

distribution in food– Injection for infants– Hemolytic anemia = destruction of red

blood cells• Toxicity

– Jaundice from large doses of vit. K, toxic effects on membrane of red blood cells, cells die, lead to increased levels of yellow bilirubin (formed from heme)

CH3

CH3

O

O CH3 CH3

Vitamin K1 (phylloquinone)

CH3

CH3

O

O CH3 CH3

Vitamin K2 (menaquinone)

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Vitamin E-tocopherol

• Function

– Antioxidant: prevents cell damage from oxidation of polyunsaturated FAs in membranes by O2 and free radicals

• Deficiency

– Associated with defective lipid transport/absorption

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Olestra• Artificial, noncaloric fat substitute (indigestible)

• FDA warning– “This Product Contains Olestra. Olestra may cause abdominal cramping

and loose stools. Olestra inhibits the absorption of some vitamins and other nutrients. Vitamins A, D, E, and K have been added.”

O

CH2

H O

HCH2

O H

CH2

OH

O

H

H

OH

O

H

O

OC

O

R

O

C

R

O

C

R

O

C

R

O

O

C

R

O

C

R

O

C

R

O

O

R

KRT-2011 88

Eicosanoids • Hormones involved in production of pain, fever, inflammatory

reactions– Prostaglandins– Thromboxanes– Leukotrienes

• Metabolites of arachidonic acid (a polyunsatruated FA)• Synthesis inhibited by NSAIDs

– e.g. acetylsalicylic acid (aspirin)– Acylate Ser residue, preventing access to active site

45

KRT-2011 8989

Structure of a biological membrane

• A lipid bilayer with associated proteins

KRT-2011 90

lipid - universitas brawijayablog.ub.ac.id/virgus/files/2013/06/01_lemak.pdf · lipid functions 1....

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