Membrane Lipids: Properties, Structure and Classification by easybiologyclass

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2. [AW BIOLOGY CLASS "Good fences make good neighbors” Robert Frost, "Mending Wall, " In North of Boston, 1914

3. I . . ,., ..Y ' Learning objectives: I Understand the organization of membrane system I Properties of membrane lipids I Classification of membrane lipids I Structure of membrane lipids I Structure and properties of : - : Glycolipids : Phospholipids : Sphingolipids : Sterols : Archaebacte‘rial Ether Lipids n l I‘ II! " “I I l I‘ I. H . _ l ‘/ ll IM/ lid‘ l‘II" A ‘:15 lit / /:, ’Il‘ ”H"V/ V,II4l». ‘lIi. ll? ‘ / -fl‘? IQ V“ ‘/ ‘V-. ‘¢'Il/ ;“l | ;““~ ‘ wirw. east-'biol0g_'cIa5s. com

4. MEMBRANE LIPIDS ' , ‘ EASY BIOLOGY CHM Biological membrane system: I Membranes are two layers thick sheath like structures I Formed by non-covalent assemblage of lipids and proteins I Mainly consists of Lipids, Proteins and Carbohydrates I Thickness of membrane: 60 A (6 nm) to 100 A (10 nm) I Membrane forms closed boundaries between different compartments I Act as barriers to the passage of polar molecules and ions rlrlrlrlrlrlrlrlrlrlrlrllrllrlrlrlrltlrl Plasma membrane 4

5. MEMBRANE LIPIDS 7 . MW BIOLOGV (LAOS I Membrane lipids have hydrophilic (polar) & hydrophobic (non-polar) parts (_ Po, ar. Head. gmup I One end is hydrophilic and the other end is hydrophobic (amphipathic) I Their hydrophobic interactions with each other Nan-Polar ‘Tail’ Groups and their hydrophilic interaction with water direct the packing of lipids in the membrane M°“‘b”“‘ UP“ _ Polarkegion 11 ml Lipid Layer 1 Lipid Layer2 I Polar Region I— , Lipid Bilayer of Plasma Membrane

6. MEMBRANE LIPIDS c I (“V BIOLOGY (M15 <§> Bio-membranes are asymmetric Components of two faces always differ from each other <§> Long hydrocarbon chains of fatty acid forms the hydrophobic part <§) Hydrophilic moieties of the membrane lipids may be as simple as single —0H at one end of the sterol ring system or they may be much complex We commonly represent the polar part of membrane lipid as ‘Head’ and the non-polar part as ‘Tail’ In the coming slides we will see the structure and classiﬁcation of membrane lipids M “H” m"MM| W mu“ lnmmwm in h "I i‘

7. MEMBRANE LIPIDS IASV BIOLOGY (LAM > Membrane lipids are classified based on the properties of ‘head’ group > Membrane lipids of Prokaryotes, Eukaryotes and Archaebacteria are grouped into Four major categories: 1. Phospholipids 2. Glycolipids 3. Sterols 4. Archaebacterial ether lipids M “I "MM Ml mu“ Hlmmwnl in h ml in

8. MEI‘/ iBRAllE LIPIDS Mind-Map: Classiﬁcation chart of Membrane Lipids 3 2' Phospholipids ’l’’’e_: ’’’’’, ’’, a’’e : Glycolipids ; Sterols 3‘ Archaebacterial ether lipids www. easybiologyclass. com

9. MEMBRANE LIPIDS ’ 3 II EASY BIOLOGY (LAOS Membrane lipids classification: 1. Phospholipids > Glycerophospholipids > Sphingo-phospholipids 2. Glycolipids > Galactolipids [sulfolipids] > Sphingo-glycolipids 3. Sterols 4. Archaebacterial ether lipids

10. MEMBRANE LIPIDS II IASV BIOLOGY (LAOS (1 ). Phospholipids: O Glycerol-3-phosphate is the backbone of all phospholipids 0 Here a polar head group is joined to the hydrophobic moiety by a phosphodiester linkage O Other two —OH groups (C1 and C2) are esterified by fatty acids (R1 & R2) , (|IH2—0H ‘fl I - R —c—o—c’— H 0 ICH2—0 — P-0 ’ II I u I 0 3cH2—O — P—O— I OH OH Glycerol-3-Phosphate Glycerophospholipid

11. MEMBRANE LIPIDS (1). Phospholipids: I There are two major class of Phospholipids: A. Glycero-phospholipids B. Sphingo-phospholipids . . caumniuua. (eIr§, I«.1IIIsIrI. Ls ’ Em . ‘I« m‘. m': ‘I*-:12”: -. I’ -(-. f:’. -r. :'. I’ am’ H1‘ 2-

12. MEI‘/ iBRAllE LIPIDS ( 1). Phospholipids: (A) Glycero-phospholipids: -CHz—0H - in Also called as phosphoglycerides ! |cH2_0 _ P_0- I OH Glycerol-3-Phosphate Consists of glycerol-3-phosphate, whose C1 & C2 esterified by fatty acids Major lipid component of biological membrane The C3 is linked to a polar group - ‘X’ In simplest glycero-phospholipid, the ‘-X’ is - H, is called phosphatidic acid H, -‘J . .-I 0 ll lCH2:O'*C: Rl I . Glycemphospholipld 7 wwweasybiologyclass. com 1‘

13. ? MEl/ iBRAllE LIPIDS . : V'- ' ~2"EASY Ph ospho-glycerolipids are of different types based on ’X’ group ( table ) n : cHz—n—1 — R» R_. ~u‘—()—1f— II ‘T .3 ‘| c": —0—l’—()—X J. ” an uuuu uphtnplmllpd-I www. easybiologyclass. com Water _ Phosphatidicacid Ethanolamine —CH2CH2NH3* Phasphatidylethanolamine Choline -CH2CH2N(CH3)3* Phosphatidylchaline(Lecithin) Serine —CH2CH(NH3*)CO0' Phasphatidylserine Glycerol —CH2CH(0H)CH20H Phasphatidylglycerol -OI. G1[0M)(ll. — . —« —cn_. _ _ . ’ ' D h h td II I Phosphatldylglycerol 0' ° "*1 {C'gr; ?:)’; ip‘: n')y‘qycero Myo-inositol Phosphatidylinositol

14. MEMBRANE LIPIDS ' . _ II IASV BIOLOGY “M5 (1 ). Phospholipids: (A) Glycero-phospholipids: O Cardiolipin: an important component of the inner mitochondrial membrane 0 It constitutes 20% of the total lipids of inner mitochondrial membrane 0 The only other place where Cardiolipin can be found is in the membranes of most bacteria 0 Thus it is an evidence for endosymbiont theory K O o o o)| R3 “2 0 II 0H u U—-P—() )/ U—'P—U R4 I I 0 u 0 Cardiolipin (Diphosphatidylglyceral)

15. MEMBRANE LIPIDS ' , II EASY BIOLOGY CHM (1 ). Phospholipids: (A) Glycerophospholipids: Plasmalogen: 0 They are glycero-phospholipids in which the C1 of glycerol moiety is linked via an or, B-unsaturated ether linkage rather than an ester linkage O Ethanolamine, choline & serine are the most common plasmalogen heads 0 Function of plasmalogens are not well understood Ether Linked Alkene Ether Llnkale / /_/ /_/ // . ?H2—o—cH= cH—R, '‘i”2’° 551" Unk-‘I8l‘ . H _c2_ 0_c R2—c—o—c‘— H ('3' ll 0 3|cH2_o _ p_o_ Choline | ‘cH, —o — p—o—cH, —cH, —N*(cH, ) , OH I 0. ll 0 0 ll Plasmalogen Backbone Plasmalogen E

16. MEMBRANE LIPIDS "l 5 II IASV BIOLIMY GUM (1). Phospholipids: ( B). Sphingo-phospholipids: I Major class of membrane lipids I Named after Sphinx because of their function in the cells was mysterious I Most of the spingolipids are derivatives of C18 amino alcohol Sphingosine I N-acyl fatty acid derivative of sphingosine are known as ceraminde Sphingosine “'0 ]. |{ (| )H HIO II-I IOH H2C— (|3—(|3—H HzC— <|3—<|3—H H3N* ICIIH HT ﬁll ? " f T" C (‘|3H2)12 R ((|3H2)12 Sphingo-phospholipid CH3 CH3 Sphingosine Imhmm Ceramide W

17. MEMBRANE LIPIDS (1). Phospholipids: (B). Sphingo-phospholipids: Sphingomyelins Electron Micrograph of Myelinated Nerves: membrane around each nerve axon. Myelin sheath may be 10 -15 layers _ A thick and the high lipid content makes ( it an electrical insulator mix Most common sphingolipid ICHII H, c— N’— CH3 [ Make up 10 — 20% of plasma membrane lipids I 3-4 G"! -re , , mphmr~. mnt They are ceramides with phosphocoline or o= ;|»_ o- | _. phosphoehtanolamine head (I) III on _ _ H, c— C—C—H Myelin sheath of nerve cell axons are rich in I I HN CH h‘ ' " I uiemmide sp lngomyellns M 0=c CH Fatty And I | I “(H20 (cH2)l2 See the spirally wrapped ‘ H3‘: CH3 ‘ Sphlngomyelin

18. MEMBRANE LIPIDS ' , II IASV BIOLOGY am (2). Glycolipids: O Lipids conjugated with carbohydrates 0 Three main role: 0 Part of biological membrane system 0 Provide energy 0 Markers for cellular recognition (LH-,0H )cH_ o_ C / /'/ /-= /&/ / 0 I II HO H 0- ‘CH2 0 0" H um-n a "M43: H Glycolipid H OH 11

19. 1‘/ lEMBRAllE LIPIDS (2). Glycolipids: A Classification of Glycolipids: Ixlcliilirziiic? : Glycolipids ' In: I = 3 A www. easybiologyclass. com 19

20. MEMBRANE LIPIDS ’ : 5 II IASV BIOLOGY GUM (2). Glycolipids: Different class of glycolipids are: > (A). Glyceroglycolipids: Glycerole backbone with carbohydrates a) Galactolipids b) Sulfolipids > (B). Sphingo-glycolipids: Sphingosine backbone with carbohydrates a) Cerebrosides b) Globosides C] Gangliosides

21. MEMBRANE LIPIDS ' , II [MY BIOLOGY am (2). Glycolipids: (A). Glycero-glycolipids: —> Galactolipids I One or two galactose residues present I Galactose connected by a glycosidic linkage to C3 of a Glycerol I C1 and C2 of glycerol are esterified with fatty acids 0 ll . CH2— 0- c / // /%/ ;—/ / cH, oH I Fan‘ And Ilrsuduc Galactolipid Monogalactosyldiacylgb/ cerol (MGDG) H OH l. .u'hoOIVdr'. Ilr Residue

22. MEMBRANE LIPIDS IASV BIOLOGY (MM (2). Glycolipids: (A). Glycero-glycolipids: —> Galactolipids I Galactolipids are predominant in plant cells I They are abundant in thylacoid membrane of chloroplasts I They constitute ~ 70% to 80% of membrane lipids of vascular plants I Probably they are the most abundant membrane lipids in the biosphere III “I "MIMI III mllm IIIIIIWMII III II III in

23. MEMBRANE LIPIDS EASY BIOLOGY (MM 1“ Galactolipids of chloroplasts: 0 II ‘CH2: 0: C $ _ I Ian A. nIlt--uIn. - (HIGH __c“ _ o_ C / // / 0 I II Ho H o— ‘cu, o H I-MTIUQIIIII IIIIKDQV Monogalactosyldiacylglycerol H on (MGDG) cH, oH H0 H 0 H Digalactosyldiacylglycerol (MGDG) OH H (II ' °‘C": cH2_ o_c H OH (| ;H _ o_ C / // /= /—/ / 0 I II H0 H 0-— CH, 0 on H H OH

24. MEMBRANE LIPIDS ' , ‘ 5 II EASY IOOLOGV (IAN! (2). Glycolipids: (A). Glycero-glycolipids: —> Sulfolipids: > A class of glycero-glycolipid with sulfur containing functional groups > Sulfonated glucose is joined to the C3 of diacylglycerol in glycosidic linkage > Plant membranes also contain sulpholipids > Sulfonate head hold negative charge (like phosphate group in phospholipids) Sulfolipid

25. 1VlEMBRAllE LIPIDS ‘ " ' s2"EASY ~ (2). Glycolipids: (B). Sphingo-glycolipids: A A category of glycolipid - Contains an amino alcohol sphingosine instead of glycerol » N-acyl fatty acid derivative of sphingosine are known as ceramide A Sphingo-glycolipids includes: Ho H OH H0 1'; OH I I I | I (1) Cerebrosides H2C— $— ?7— H H2C— (|3_ ‘| :_ H _ _ H N» CH HN CH b) Gangllosldes 3 H I H (| :H 0 —$ CIH c Globosides 'I~'-'5-‘mi’-fa‘-i'u‘-3’ } ("3H2)12 R (CH2]12 I CH3 CH3 Sphingosine ceramide I») UI www. easybiologyclass. com

26. MEMBRANE LIPIDS ' , II EASY BIOLOGY CHM (2). Glycolipids: (B). Sphingo-glycolipids: a). Cerebrosides: I It is a ceramide with single sugar residue at the C1-hydroxyl moiety I Sugar residue can be either glucose or galactose I Thus two categories: Glucocerebrosides, Galactocerebrosides I Cerebrosides lack phosphate groups and thus they are nonionic (no charge) I Abundant in animal muscle and nerve cell membranes I Galactocerebrosides are typically found in nerves Cerehroslde (H_,0ll 1‘ 1”‘ o — cn, — ? —|c—u an cu ( l‘1.Ilﬂ| d(‘ I " ' llrsnlur I Glucocerebrosides are found in other tissues 0 = (' Cl" H OH R (C“2)I. ' I CH, Cavhohyliralr Residue

27. MEMBRANE LIPIDS II EASY BIOLOGY CHM (2). Glycolipids: (B). Sphingo-glycolipids: b). Globosides: I A sphingo-glycolipid with more than one sugars as side chain of ceramide I Sugars are usually a combination of N -Acetylgalactosamine, D-glucose or D- galactose 0 O“ 0“ Jk OH OH Hr‘; R 0 0* O Q 0 0 0 O '3" 0 oH ‘ 0 0“ . ‘ 5,. OH ‘ ‘ ‘ SH ‘ u-m"/ AH 0 Globoside

28. MEI‘/ lBRAllE LIPIDS ’“ ' . .-“usv (2). Glycolipids: (B). Sphingo-glycolipids: c}. Gangleosides: A glyco-sphingolipid (ceramide & oligosaccharide) with one or more sialic acids linked on the sugar chain A Most complex sphingo-glycolipid - _c/ l 6% of brain lipids are gangleosides ~«—<f V cu / ‘ii; -i. ‘ A A First isolated from ganglion of brain cells / ;= Abundant in lipid-rafts of plasma membrane ‘TL / ' i- —s~~- * » ‘, ". ‘ . . / ‘ ~, r a . _ V, /if . , , :I. ‘:, ‘_ '{_. .‘; -‘l, _'’ ‘an " -4 _. . _‘: ‘~35’ {. ?."? ‘.s A Gangliosvde 3 www. easybioIogycIass. com * , ‘- ’ - Q ‘ V , , ‘ rﬁ "

29. MEMBRANE LIPIDS ' , ‘ EASY BIOLOGY GM“ (2). Glycolipids: (B). Sphingo-glycolipids: c). Gangleosides: Physiological / Medical significance of Gangleosides: Considerable physiological and medical significance Act as specific receptors for glycoprotein hormones Act as receptors for some bacterial protein toxins such as cholera toxin Act as speciﬁc determinants of cell—cell recognition [important in growth and differentiation of tissues and in carcinogenesis) Tay-Sachs disease is a hereditary disorder of ganglioside breakdown leading to fatal neurological deterioration in the early childhood

30. MEI! /iBRAIIE LIPIDS is ' . .-“usv l (3). Sterols: on I Third major class of membrane lipids I Usually present in the membranes of eukaryotic cells Cyclopentanoperhydrophenanthrene I Sterol consists of four fused carbon rings (A, B, C, D) and an alkyl side chain I Alkyl chain is called ‘hydrocarbon side chain ' I Ring A, B and C are with six carbons and Ring D is with ﬁve carbons I This fused ring is called the Steroid Nucleus I Steroid nucleus is derived from cyclopentanoperhydrophenanthrene I Fused ring structure do not allow C — C free rotation 30 www. easybiologyclass. com

31. MEMBRANE LIPIDS ' . ‘ II EASY BIOLOGY GLASS (3). Sterols: I Cholesterol is a major sterol of animal membranes I Constitute about 30-40% all membrane lipids in animals I Cholesterol is amphipathic with polar hydroxyl (—OH) ‘head’ and non- polar hydrocarbon ‘tail’ I The —OH and the hydrocarbon chain are attached to the C3 and C17 of steroid nucleus respectively CH , ,cH . 'I 3 3 I ‘CH — (CH2)3 —c H H3C: u __. cH3 Cholesterol

32. MEMBRANE LIPIDS E 1 II (MY BIOLOGY CLASS 2 (3 ). Sterols: I Cholesterol can esterify with long chain fatty acids to form cholesteryl esters such as cholesteryl stearate (‘EH3 CH3 cn — (CH2)3 —c — H H3C | Q H3C O I Cholesteryl stearate C I

33. MEMBRANE LIPIDS ' . II EASY BIOLOGY GLASS j (3 ). Sterols: I In mammals, cholesterol is the metabolic precursor of steroid hormones I Cholesterol very rarely found in plants (other sterols occurs in plants) I Stigmasterol: important membrane sterol in plants (phytosterol) I Campesterol and sitosterol are other plant sterols I Ergosterol: sterol found in fungal membrane system

34. MEMBRANE LIPIDS ' . II EASY BIOLOGY GLASS ( 3 ). Sterols: I Bacteria cannot synthesize any sterol I Thus bacterial membrane generally lacks sterol I Some bacteria can incorporate exogenous sterol in to their membrane I Lanosterol: sterol precursor of animals and fungi I Cycloartenol: sterol precursor of plants I Both Lanosterol and Cycloartenol are derived from the cyclization of triterpenoid - squalene

35. MEMBRANE LIPIDS ’ : 5 (4). Archaebacterial ether lipids: IASV BIOLOGY GUM G Iyrerul ' unm- linkage mpmhmxl Fourth major class of membrane lipids They are membrane lipids of archaebacteria Glvcerol Absent in prokaryotes and eukaryotes Archaebacterial Ether Lipid Majority of archaebacteria lives in extreme conditions (high temperature) Archaebacterial ether lipids contain long (32C) branched hydrocarbon chains linked at both end to glycerol Linkages are through ether bonds (R — O — R’)

36. MEMBRANE LIPIDS 2 ( 3). Archaebacterial ether lipids: I Ether bonds are more stable than ester bonds I They are twice the length of phospholipids and sphingolipids I They span the width of the surface membrane I At each end of the molecule two glycerol moieties are present I This glycerol is linked to either phosphate or sugar residues hliu-nnljilmspiialr "J: "sf aau(p: ~2)w-1 . "‘$ lupin nuwl I hum M“ N”. Archaebacterial Ether Lipid Archaebacterial Ether Lipid E

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