Carbohydrates III; Lipids ISugar Complexes and LipidsPlans for TodayGlycoconjugatesProteoglycans: GlycosaminoglycansProteoglycans in cartilagePeptidoglycans (G&G fig. 7.29)Peptidoglycans in bacteriaPeptide component (G&G fig. 7.29)Gram-negative bacteria: the periplasmic space (G&G fig. 7.30b, 7.31)Gram-negative membranes and periplasmic spaceGlycoproteinsDiversity in glycoproteinsO-linked and N-linked oligosaccharidesO-linked oligosaccharides (fig. fig 7.32a, 7.33 in G&G)N-linked oligosaccharides (fig. 7.32b,c in G&G)iClicker question 1iClicker question 2LipidsPeriodic table of lipidsFatty acidsTrans fatty acidsFatty acids: melting points and structuresSources for fatty acidsTriglyceride composition by sourceNomenclature for fatty acidsSaturated Fatty AcidsHow fatty acids really appearTriacylglycerolsCatabolism of triacylglycerolGlycerophospholipidsCategories of glycerophospholipidsVarieties of head groupsPhospholipids aren’t interchangeable!Chirality in common lipidsiClicker quiz question 3iClicker quiz, question 4iClicker quiz question 5PlasmalogensSpecific plasmalogensRoles of phospholipidsSphingolipidsVarieties of sphingolipidsCerebrosidesGangliosidesIsoprenoidsIsoprene units: how they’re employed in real moleculesSteroidsOther lipidsExample of a wax09/21/2010Biochem: Carbo III, Lipids ICarbohydrates III;Lipids IAndy HowardIntroductory Biochemistry, Fall 201021 September 2010As delivered by Nick Menhart09/21/2010Biochem: Carbo III, Lipids Ip. 2 of 50Sugar Complexes and LipidsSugars form complexes with proteins and lipidsLipids are critical as energy storage molecules and as components of membranes09/21/2010Biochem: Carbo III, Lipids Ip. 3 of 50Plans for TodayGlycoconjugatesProteoglycansPeptidoglycansGlycoproteinsLipidsClasses of lipidsFatty acidsTriacylglycerolsLipids, continuedGlycero-phospholipidsPlasmalogensSphingolipidsIsoprenoidsSteroidsOther lipids09/21/2010Biochem: Carbo III, Lipids Ip. 4 of 50GlycoconjugatesPoly or oligosaccharidescovalently linkedto proteins or peptidesGenerally heteroglycansCategories:Proteoglycans (protein+glycosaminoglycans)Peptidoglycans (peptide+polysaccharide)Glycoproteins (protein+oligosaccharide)Image courtesy Benzon Symposia09/21/2010Biochem: Carbo III, Lipids Ip. 5 of 50Proteoglycans: GlycosaminoglycansUnbranched heteroglycans of repeating disaccharidesOne component isGalN, GlcN, GalNAc, or GlcNAcOther component: an alduronic acid—OH or —NH2 often sulfatedFound in cartilage, joint fluid09/21/2010Biochem: Carbo III, Lipids Ip. 6 of 50Proteoglycans in cartilageHighly hydrated, voluminousMesh structure (fig.7.36 or this fig. from Mathews & Van Holde)Aggrecan is major proteoglycanTypical of proteoglycans in that it’s extracellular09/21/2010Biochem: Carbo III, Lipids Ip. 7 of 50Peptidoglycans(G&G fig. 7.29)Polysaccharides linked to small proteinsFeatured in bacterial cell walls:alternating GlcNAc + MurNAclinked with -(14) linkagesLysozyme hydrolyzes these polysaccharidesPeptide is species-specific:often contains D-amino acids09/21/2010Biochem: Carbo III, Lipids Ip. 8 of 50Peptidoglycans in bacteriaGram-negative: thin peptidoglycan layer separates two phospholipid bilayer membranesGram-positive: only one bilayer, with thicker peptidoglycan cell wall outside itGram stain binds to thick wall, not thin layerFig. 7.30 shows multidimensionality of these walls09/21/2010Biochem: Carbo III, Lipids Ip. 9 of 50Peptide component(G&G fig. 7.29)Sugars are crosslinked with entities containing(L-ala)-(isoglutamate)-(L-Lys)-(D-ala)Gram-neg: L-Lys crosslinks via D-alaGram-pos: L-lys crosslinks via pentaglycine followed by D-ala09/21/2010Biochem: Carbo III, Lipids Ip. 10 of 50Gram-negative bacteria:the periplasmic space(G&G fig. 7.30b, 7.31)Periplasmic space: space inside cell membrane but inside just-described peptidoglycan layer (note error in fig. legend!)Peptidoglycan is attached to outer membrane via 57-residue hydrophobic proteinsOuter membrane has a set of lipopolysaccharides attached to it; these sway outward from the membrane09/21/2010Biochem: Carbo III, Lipids Ip. 11 of 50Gram-negative membranes and periplasmic spaceQuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Figure courtesy Kenyon College microbiology Wiki09/21/2010Biochem: Carbo III, Lipids Ip. 12 of 50Glycoproteins1-30 carbohydrate moieties per proteinProteins can be enzymes, hormones, structural proteins, transport proteinsMicroheterogeneity:same protein, different sugar combinationsEight sugars common in eukaryotesPTM glycosylation much more common in eukaryotes than prokaryotes09/21/2010Biochem: Carbo III, Lipids Ip. 13 of 50Diversity in glycoproteinsVariety of sugar monomers  or  glycosidic linkagesLinkages always at C-1 on one sugar but can be C-2,3,4,6 on the other oneUp to 4 branchesBut:not all the specific glycosyltransferases you would need to get all this diversity exist in any one organism09/21/2010Biochem: Carbo III, Lipids Ip. 14 of 50O-linked and N-linked oligosaccharidesCharacteristic sugar moieties and attachment chemistries09/21/2010Biochem: Carbo III, Lipids Ip. 15 of 50O-linked oligosaccharides(fig. fig 7.32a, 7.33 in G&G)GalNAc to ser or thr;often with Gal or Sialic acid on GalNAc5-hydroxylysines on collagen are joined to D-GalSome proteoglycans joined viaGal-Gal-Xyl-serSingle GlcNAc on ser or thr09/21/2010Biochem: Carbo III, Lipids Ip. 16 of 50N-linked oligosaccharides (fig. 7.32b,c in G&G)Generally linked to AsnTypes:High-mannoseComplex(Sialic acid, …)Hybrid(Gal, GalNAc, Man)Diagram courtesy Oregon State U.09/21/2010Biochem: Carbo III, Lipids Ip. 17 of 50iClicker question 1Suppose you isolate a polysaccharide with 5000 glucose units, and 3% of the linkages are 1,6 crosslinks. This is:(a) amylose(b) amylopectin(c) glycogen(d) chitin(e) none of the above.09/21/2010Biochem: Carbo III, Lipids Ip. 18 of 50iClicker question 2Suppose you isolate an enzyme that breaks down -1,4-glycosidic linkages between GlcNAc units. This would act upon:(a) glycogen(b) cellulose(c) chitin(d) all of the above(e) none of the above.09/21/2010Biochem: Carbo III, Lipids Ip. 19 of 50LipidsHydrophobic biomolecules;most have at least one hydrophilic moiety as wellAttend to “periodic table of lipids”(next