Biochemistry

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Bio ChemistryLipids

Lipids are organic compounds characteristic by their insolubility in

water (All Lipids are hydrophobic) and their solubility in

organic solvent So, extracted from tissues by non-polar solvents..

essential source of energy.

main component of cell membrane.

Lipids are transported in blood as large macromolecules

•Functions of lipids in the body:1. it’s source of energy.2. It's stored energy in the body .3. Contain essential fatty acids .4. Carrier of fat soluble vitamins .5. It's thermal / electrical insulator .6. Lipoproteins = lipid + protein = Transport of fat soluble

substances.7. Types:-

1) LDL = low denisty lipoprotein .2) HDL = high denisty lipoprotein

8. structre proparites of lipiid

Classification of lipid

CLASSIFICATION

1- Simple Lipids : non – polar + energy storage

Simple lipids can be segregated into structural types, which are fattyacids (FA), waxes, triglycerides (TG), and sterols.

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Complex Lipids : polar lipid

They are lipids derived from above groups after hydrolysis (fattyacids ) .

*.* type of simple lipide :1- waxes

2- Sterol esters :

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Contain free sterols , the sterols : are esterifies to fatty acids andcalled as sterol esters .Ex,Cholestrol : from animals Beta sitosterol : from plants

3- Acylglycerol : glycerol as monoacylglycerols (MG) , diacylglycerols(DG), triacylglycerols (TG) , they are important in absorption anddigestion of fats .

What Is the Difference between Fats and Oils?Answer

- fats are solid at room at room temperature .- oils are liquid at room temperature.- Fats are usually derived from animals- oils are from plants.

Formation of triglycerides When glycerol reacts with three fatty acids, it forms triglycerides

+ 3RCOOH

CH2OHCHOHCH2OHGlycerol

CH2OCORCHOCORCH2OCOR

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- :التسمیة 1- or - + mono, tri,.. + in ووضع IC حذف .

أسم الحمض مع حذف یك ووضع - ١مختلط ثالثى أسیل جلیسرول-٢جلیسرول-Sn–ول

H2C1

C2

H

3

HO

H2C

OH

OH

L-propane-1,2,3-triol

MonoglyceridesIf glycerol react with one

molecule of fatty acid

Diglycerides.If glycerol react with two

molecules of fatty acid

TriglyceridesIf glycerol react with 3 molecules of

fatty acid

CH2OCOR1

CHOHCH2OH

CH2OCOR1

CHOCOR2

CH2OH

CH2OCORCHOCORCH2OCOR

Biochemistry

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saponifacationكحول +أحماض دھنیة :اللبیدات البسیطة - ١:الزیوت والدھن والشموع : أمثلتھا Lipids precursorsبادئات اللیبید

مواد أخرى+ كحول + أحماض دھنیة : أمثلتھا :اللبیدات المركبة - ٢).Lipo protein= جلیسولیبید =سربورسید–دھنیات فوسفاتیة (

اد الملونة وأنواعھا من مثل المو) :الدھنیات المشتقة(اللبیدات المشتقة - ١للتصبنةغیر قابل.األستیروالت

emulsification of lipids:-

(chemistry) The process of dispersing one liquid in a second immiscible liquid; the largest group of

emulsifying agents are soaps, detergents, and other compounds, whose basic structure is a paraffin

chain terminating in a polar group.

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Compound lipids- Lipids: phospholipids اللیوفوسفولیبیدات

Phosphatidic acids (PAs) + Hydroxyl compound .-:األحماض الفوسفاتیة

..لھا دور فى التخلیق الحیوى

P

O

OH

OH

CH2OCOR

CHOCOR1

CH2O

Polar compound by H2PO3 group .- 1- Phosphatidylcholine = lecithin = PC .

Phosphatidylcholines (PC) are a class of phospholipids that

ncorporate choline as a headgroup. They are a major component of biological

membranes and can be easily obtained from a variety of readily available

sources, such as egg yolk .

FUNCTION :- It is thought to be transported between membranes within the

cell by phosphatidylcholine transfer protein (PCTP).

P

O

O

OH

CH2OCOR

CHOCOR1

CH2O (CH2)2 N

CH3

CH3

CH3

Lecithin=phosphatidyl choline

P

O

O

OH

CH2OCOR

CHOH

CH2O (CH2)2 N

CH3

CH3

CH3

Lysolecithin

By phospholipase D (PLD), via the hydrolysis of the P-O bondof phosphatidylcholine (PC) to produce PA and choline.

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2- phosphatidyl ethanolamine = PE

).فوسفاتیدیل إیثانول أمین( الكیفالینات

P

O

O

OH

CH2OCOR

CHOCOR1

CH2O (CH2)2 NH2

3- Phosphotidylserin = PS.

). فى المخ(فوسفاتیدیل سیرین

P

O

O

OH

CH2OCOR

CHOCOR1

CH2OH2C

HC NH2

COOHEssential component of phospholipid bilayer of cell membranes

عنصر أساسي من طبقة ثنائیة فسفولیبید أغشیة الخالیا

4- Phosphotidylinositol = PI.

-) :حیوانى ونباتى( فوسفاتیدیل األنیوسیتول

Essential component of phospholipid bilayer of cell membranes

عنصر أساسي من طبقة ثنائیة فسفولیبید أغشیة الخالیا

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Phospholipase= enzymatic hydrolysis

A phospholipase is an enzyme that hydrolyzes phospholipids[1] into fatty acids and

other lipophilic substances. There are four major classes, termed A, B, C and D, distinguished by

the type of reaction which they catalyze:

Phospholipase A

Phospholipase A1 - cleaves the SN-1 acyl chain.

Phospholipase A2 - cleaves the SN-2 acyl chain,

Phospholipase B - cleaves both SN-1 and SN-2 acyl chains; =lysophospholipase.

Phospholipase C - cleaves before the phosphate, releasing diacylglycerol and a

Phospholipase D - cleaves after the phosphate, releasing phosphatidic acid and an

alcohol.

Types C and D are considered phosphodiesterases.

Example :-

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HydrolysisComplete hydrolysis of phospholipids is easily affected byacidic media and with alkali the acyl groups are split .PC -----strong acid hydrolysis choline + glycerophosphoric acid + 2 FAS.

PC -----mild alkali hydrolysis Fas from 1 and 2 positions + glcerophosphatidyl choline (GPC) .

SphingophospholipidsAll contain

sphingosin

CH3(CH2)12 CH CH CHOH

CHNH2

CH2OH

Shingo lipids contain faty acids but none contain glycerol

Example :-

ceramide sphingomeilin

Sphingosin bond to fatty acid through anamide linkage .

Sphingosin bond to fatty acid through anamide linkage and other linkage withphospholipid.

Function :-

Found at nervous system , surrounding the fastest conducting nerve fibers .

Glyco lipidsLipids containing carbohydrate .

2 classes :-

1- Cerebrosides : consist of hexose sugar , they are formedof the myelin of the nerve axonsالمحاور العصبیة

2- Gangliosides :carbohydrate protion is very complex , theygray matter of brain is rich in gangliosides.

gangliosidesنھم المادة الرمادیة من الدماغ غنیة

derived lipidsvery complex as cholesterol

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trans - fatty acids and (lDl) raises plasma concentration oflipoprotein and low risk of heart attack but cis- fatty acids and(HDl) decrease plasma concentration of lipoprotein and low riskof heart attack

Fatty acid1- The main costituent of many lipids .

2- Have asingle carboxyl group (polar) and longhydrocarbon chain (non-polar) .

Nomenclature

Not, ……

Geometric Isomerism

C C

H H

CH3

Trans-Cis-

CH3(CH2)4

C C

H

H

CH3

CH3(CH2)4

C C

H CH3

CH3CH3(CH2)4

No,Cis-No,Trans-

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Oleic acid C 18 C-9 ------(18:1c Δ9) or (18:1t Δ9) ώ9. في زیت الزیتون

Ex: CH3(CH2)7CH=CH-(CH2)7COOH.

CH3(CH2)7

H H

(CH2)7COOH

Cis-

CH3(CH2)7

H

H

(CH2)7COOHTrans-

Physical proparites :- m.P or B.P

1- Unsaturated faty acid < saturated faty acid .

2- Cis – form ( curved structure) < trans – form (linear structure ) .

3- Longer chain > short chain .

Hydrogenation of unsaturated fatty acid :H2/ Ni

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Synthesis of Vitamin D in the Skin by Sunlight

Cholesterol--- 7-Dehydrocholesterol Vitamin D

StructureAcid Name

CH3(CH2)2COOHButyric

CH3(CH2)10COOHLauric

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Essential fatty acid- Essential fatty acids, or EFAs, are fatty acids that humans and other

animals must ingest because the body requires them for good healthbut cannot synthesize them

- "essential fatty acid" refers to fatty acids required for biologicalprocesses .

Examples:The essential fatty acids start with the short chain polyunsaturated fatty acids (SC-PUFA):

ω-3 fatty acids:

α-Linolenic acid or ALA (18:3n-3) ω-6 fatty acids:

Linoleic acid or LA (18:2n-6)

These two fatty acids cannot be synthesized by humans because humans lackthe desaturase enzymes required for their production.

They form the starting point for the creation of longer and more desaturated fatty acids,which are also referred to as long-chain polyunsaturated fatty acids (LC-PUFA):

ω-3 fatty acids:

eicosapentaenoic acid or EPA (20:5n-3)

docosahexaenoic acid or DHA (22:6n-3) ω-6 fatty acids:

gamma-linolenic acid or GLA (18:3n-6)

dihomo-gamma-linolenic acid or DGLA (20:3n-6)

arachidonic acid or AA (20:4n-6)

ω-9 fatty acids are not essential in humans because they can be synthesized fromcarbohydrates or other fatty acids

fuction of …..- Arachidonic acid (AA, sometimes ARA)-------- present in the phospholipids

of membranes of the body's cells, and is abundant in the brain, muscles, and liver.- Hormones are chemical messengers secreted by cell or gland. These messengers

are sent out from one part of the body to affect cells in other parts of the body- Chylomicrons transport exogenous lipids to liver, adipose, cardiac, and skeletal

muscle tissue, where their triglyceride components are unloaded by the activity oflipoprotein lipase. As a consequence, chylomicron remnants are left over and aretaken up by the liver.