生物化學(xué)上冊(cè)雙語(yǔ)

1Chapter2.CarbohydratesIntroductionMonosaccharides(單糖)Oligosaccharides(寡糖)Polysaccharides(多糖)Glycoconjugates(復(fù)合糖)Analysisofcarbohydrates2I.IntroductionExistenceFunctions(功能)Definition(定義)Classification(分類)Characteristicchemicalfeatures(化學(xué)通性)31.ExistenceThemostabundantclassoforganicmoleculesfoundinnatureWidelydistributedinplantsandanimalsOriginatedfromphotosynthesisBasiccomposition:C,H,O(N,P,S)Empiricalformula:(CH2O)nConstitutingaversatileclassofmoleculesMono-/oligo-/polysaccharides(單糖/寡糖/多糖)Derivatives(衍生物)Glycoconjugates(復(fù)合糖)I.IntroductionP.142.FunctionStorageofenergy(能量貯存)Structuralelements(結(jié)構(gòu)成分)Precursors(前體)/intermediates(中間物)ofotherbiomoleculesCellrecognition(細(xì)胞識(shí)別)I.IntroductionP.153.Definition葡萄糖果糖甘油醛二羥基丙酮Carbohydratesarepolyhydroxyaldehydesorketones(多羥基醛/多羥基酮)

orsubstancesthatyieldsuchcompoundsonhydrolysis.64.Classification

CarbohydrateCompositionsExamplesMonosaccharide(單糖)SimplesugarGlucose(葡萄糖)Fructose(果糖)Oligosaccharide(寡糖)2-20sugarunitsSucrose(蔗糖)Maltose(麥芽糖)Polysaccharide(多糖)>20sugarunitsStarch(淀粉)Cellulose(纖維素)ThreemajorclassesofcarbohydratesI.Introduction75.Characteristicchemicalfeatures(化學(xué)通性)Existenceofoneormoreasymmetriccenters(不對(duì)稱中心)Abilitytoexisteitherinlinearorringstructures(線狀或環(huán)狀結(jié)構(gòu))Capacitytoformpolymericstructuresviaglycosidicbonds(糖苷鍵連接)Potentialtoformmultiplehydrogenbondswithwaterorothermolecules(形成氫鍵的能力)I.IntroductionP.28Twofamilies:aldoses&ketoses(醛糖和酮糖)Stereochemistry(立體化學(xué))Structures:linear&cyclic(線狀和環(huán)狀結(jié)構(gòu))Properties:physical&chemical(物理和化學(xué)性質(zhì)) *opticalactivityandchirality(光活性和手性)Importantmonosaccharidesandtheirderivatives(重要的單糖及其衍生物)II.Monosaccharides91.Twofamilies:Aldoses&ketosesAldoses(醛糖)Ketoses(酮糖)II.Monosaccharides甘油醛二羥丙酮丙糖己糖10Plane-polarizedlight(平面偏振光)Opticalactivity(旋光性)Chirality(手性)Fischerprojections(Fischer投影式)2.StereochemistryII.Monosaccharides11(1)Plane-polarizedlight(平面偏振光)Plane-polarizedlight(平面偏振光)–alightwithitselectricvectorvibratingonaspecificplanecalledtheplaneofpolarization(偏振面)Polarimeter(偏振器)

–aninstrumentusedtomeasureopticalactivity.Polarimeter(偏光計(jì))Lightsource(non-polarizedlight)非偏振光Polarizer(偏光器)Plane-polarizedlight(平面偏振光)Sampletube棱鏡Planeofpolarizationrotated(偏振面發(fā)生了旋轉(zhuǎn))12(2)Opticalactivity(旋光性)Amaterialwhichcanrotatetheplaneoftheplane-polarizedlightiscalledtohaveopticalactivity,andthismaterialisanopticallyactivesubstance.(能使平面偏振光的偏振面發(fā)生旋轉(zhuǎn)的物質(zhì)被稱為具有旋光性)t=[]tclRotation(旋光度)Specificrotation(比旋)Concentration(濃度,g/ml)Length(dm)Wavelength(波長(zhǎng),nm)TemperatureRotationClockwise(順時(shí)針)–dextrorotatory(右旋光,+)

Counterclockwise(反時(shí)針)–levorotatory(左旋光,–)

13(3)Chirality(手性)Compoundswithoutchiralcentersdonotnormallyshowopticalacitivity.(沒(méi)有手性中心的物質(zhì)沒(méi)有旋光性)Compoundswithonechiralcenterwillshowopticalactivity.(有一個(gè)手性中心的物質(zhì)有旋光性)Compoundswithmorethanonechiralcentermayormaynotshowopticalactivitydependingonwhetherornottheyarenon-superimposableontheirmirrorimage(chiral)orsuperimposable(achiral).(有一個(gè)以上手性中心的物質(zhì)不一定有旋光性)Opticallyactivemolecule?Chiralmolecule(旋光性分子?手性分子)Opticalactivity(旋光性)?Chirality(手性)Chiralcenters(手性中心)?**14Chiralcenter（手性中心）Chiralmolecule（手性分子）Asymmetriccenter（不對(duì)稱中心）nchiralcenters2nmaximumstereoisomersTrueorfalse:Chiralmoleculesarealwaysopticallyactive. ()Opticallyactivemoleculesalwayshavechiralcenters. ()Chiralmoleculeshavealwayschiralcenters. ()Moleculeswithchiralcentersarealwayschiral. ()II.MonosaccharidesP.3n=424=16isomers15(4)Fischerprojections(Fischer投影式)投影式甘油醛(+)()RSDL透視式II.MonosaccharidesP.416FischerprojectionsHaworthprojections4C*24=16isomers8D-forms8L-formsDorLreferstotheconfigurationoftheC*farthestfromthecarbonylC.17Aldoses(醛糖)18Ketoses(酮糖)II.Monosaccharides19Twosystemsofspecifyingtheabsoluteconfigurations

(絕對(duì)構(gòu)型的兩種表達(dá)體系)Group4withthelowestpriorityD/L–referringtotheconfigurationofthemolecule(對(duì)整個(gè)分子而言)R/S–referringtotheconfigurationofaspecificC*(對(duì)單個(gè)C*原子而言)D-glucose2R,3S,4R,5R-aldohexose(己醛糖)

R/Sconvention–priorityrules+/

—referringtotheopticalactivityofthechiralmolecule(指分子的旋光性，與分子或原子的構(gòu)型無(wú)直接關(guān)系)20D-formsofmonosaccharidespredominateinnature.L-Monosaccharidesalsoexistinnature.D-glucoseistheenantiomerofL-glucose.ButD-aldohexoses(己醛糖)arenotnecessarilyenantiomersofalloftheirL-isomers.II.MonosaccharidesTheabovefourarestereoisomers.EnantiomerEnantiomerDiastereomerDiastereomer213.StructureLinearstructures(鏈狀結(jié)構(gòu))

Stereoisomers（立體異構(gòu)體）Enantiomers（對(duì)映異構(gòu)體）:P.4Diastereomers（非對(duì)映異構(gòu)體）:P.7Epimers（差向異構(gòu)體）:P.8Cyclicstructures(環(huán)狀結(jié)構(gòu))Anomers（異頭物）:P.9II.Monosaccharides22Epimers–twosugarsthatdifferonlyintheconfigurationaroundonecarbonatom.Epimersareusuallydiastereomers.(差向異構(gòu)體多是非對(duì)映異構(gòu)體)差向異構(gòu)體是僅有一個(gè)手性碳原子的構(gòu)型不同的異構(gòu)體.Anomers–Twomonosaccharidesthatdifferonlyintheirconfigurationaboutthehemiacetalorhemiketalcarbonatom.Anomersareepimers.(異頭物是差向異構(gòu)體)異頭物是環(huán)狀結(jié)構(gòu)糖分子的半縮醛/半縮酮C上形成的差向異構(gòu)體.差向異構(gòu)體異頭物甘露糖半乳糖23Hemiacetals(半縮醛)andhemiketals(半縮酮)醛酮半縮醛半縮酮縮醛縮酮Addition(加成反應(yīng))Substitution(取代反應(yīng))24Cyclicstructure(1):FormationII.MonosaccharidesP.9異頭物-Anomer-Anomer-D-吡喃葡糖-D-吡喃葡糖AnomericC(異頭碳)25Cyclicstructure(2):Haworthprojections(Haworth透射式)Whenliningupclockwisely:-CH2OHabovethering--

D-configuration-CH2OHbelowthering--

L-configuration-OHattheanomericCand-CH2OH:Ontheoppositeside

—

Onthesameside

—

DorL?or?P.10TopBottom26-D-glucoseD-glucose(Linear)-D-glucose36%<0.024%64%[]20D=+112.2o[]20D=+18.7oCyclicstructure(3):,anomersMutarotation(變旋)：在水溶液中糖的-和-異頭物之間互相轉(zhuǎn)化導(dǎo)致其旋光度發(fā)生變化的現(xiàn)象146oCm.p.148-155oCm.p.II.Monosaccharides+52.6oP.8-9-D-glucoseand-D-glucosearenotenantiomerstoeachother;theyareepimersandanomerswithdifferentproperties.(-D-glucose和-D-glucose不是互為對(duì)映異構(gòu)體，是差向異構(gòu)體和異頭物，具有不同的物理/化學(xué)性質(zhì)。)27Mutarotation(變旋)36%[]20D=+112.2o146oCm.p.64%[]20D=+18.7o148-155oCm.p.(<0.024%)Atequilibrium,[]20D=+52.6o28Cyclicstructure(4):Pyranoses&furanosesPyranoses（吡喃糖）Furanoses（呋喃糖）II.MonosaccharidesP.1029-D-吡喃葡糖-D-吡喃葡糖-D-呋喃葡糖-D-呋喃葡糖-D-吡喃果糖-D-吡喃果糖-D-呋喃果糖-D-呋喃果糖D-glucoseD-fructose30Cyclicstructure(5):ConformationForD-glucose,-formismorestablethan-form.Forotheraldohexoses,-formismorestablethan-form.Twopossiblechairconformationsof-D-glucoseII.MonosaccharidesP.13314.PropertiesPhysicalproperties(物理性質(zhì)):Opticalactivity&mutarotation(旋光性和變旋):

SeeTable1-1,P.14Sweetness(甜度):

SeeTable1-2,P.15Solubility(溶解度):

P.15

AllsolubleinH2Oexceptglyceraldehyde(除甘油醛外均為水溶性) insolubleinnonpolarorganicsolvents(不溶于非極性有機(jī)溶劑)Chemicalproperties(化學(xué)性質(zhì))II.Monosaccharides32ChemicalpropertiesIsomerization(異構(gòu)化)Oxidation(氧化)Reduction(還原)Formationofosazone(糖脎)Formationofsugarester(糖酯)andsugarether(糖醚)Formationofglycoside(糖苷)Dehydration(脫水)Elongationandshorteningofmonosaccharidechain(單糖鏈的延長(zhǎng)和縮短)II.MonosaccharidesP.153321%2.5%ChemicalProperties(1):keto-enoltautomerism(酮-烯醇互變異構(gòu))II.Monosaccharides63.5%P.15-1634ChemicalProperties(2):OxidationCH=OCH2OHOHOHOHHOCOOHCH2OHOHOHOHHOCH=OCOOHOHOHOHHOCOOHCOOHOHOHOHHOCu2++OH-Dehydrogenase(脫氫酶)HNO3Aldonicacid醛糖酸Uronicacid糖醛酸Aldaricacid醛糖二酸Sugaracids(糖酸)Br2/H2O35Oxidizingagents(氧化劑):H2O2,Ag+,Fe3+,Cu2+Fehlingreagents:tartrate(酒石酸鉀鈉)，NaOH,CuSO4Benedictreagents:citricacid(檸檬酸),Na2CO3,CuSO4Reducingsugar(還原糖):Capableofreducingoxidizingagents(可以還原以上的氧化劑)Allaldosesandmanyketosesarereducingsugars(所有醛糖和多數(shù)酮糖)Fructoseisareducingsugar(果糖是還原糖)Aqualitativetestforreducingsugars(還原糖)P.16(Redprecipitate)還原糖的定性檢測(cè)36ChemicalProperties(2):Oxidation(continued)CH=OCH2OHOHOHOHHOHHHHHCOOH4HCOOHHCHO++IO4-Thisreactionisspecificforaldoses.(此反應(yīng)只適用于醛糖)Thisreactionisusefulinprovidingstructuralinformation(此反應(yīng)可幫助分析糖的結(jié)構(gòu))II.Monosaccharides371,2-linkage1,4-linkage1,6-linkageOxidationbyIO4-P.7238ChemicalProperties(3):ReductionCH=OCH2OHOHOHOHHOCH2OHCH2OHOHOHOHHOCH2OHCH2OHOHHOCH=OCH2OHOHHOHOHONaBH4NaBH4180oRotationD-葡萄糖D-葡萄醇L-古洛糖L-古洛醇C=OCH2OHHOOHOHCH2OHC=OCH2OHHOOHCH2OHHOHOHOD-果糖L-山梨糖NaBH4NaBH4Sugaralcohols(糖醇)39Sugaralcohols(糖醇)CH2OHCH2OHOHOHOHHOD-Glucitol(D-葡萄醇)Sorbitol(山梨醇）CH2OHCH2OHOHOHHOD-Mannitol(D-甘露醇)HOCH2OHCH2OHOHOHHOD-Xylitol(D-木糖醇)CH2OHCH2OHOHGlycerol(甘油醇)HHHHHHHHHHHHII.Monosaccharides40ChemicalProperties(4):Formationofosazone（糖脎）苯肼苯脎(黃色晶體)Thisreactionisusefulincharacterizingreducingsugars(此反應(yīng)用于鑒定還原糖).YellowcrystalswithDifferentcrystalshapesDifferentmeltingpointsII.Monosaccharides41ChemicalProperties(5):SugarEsters&SugarEthers

(糖酯和糖醚)Acetylation(乙?；?Methylation(甲基化)Phosphorylation(磷酸化)P.1942OHOHHOCH2OHHHHOHHOOHOHHOCH2OHHHHO-CH3HOHemiacetal(半縮醛)Acetal(縮醛)Glycone(糖基)Aglycone(配基)Glycosidicbond(糖苷鍵)ChemicalProperties(6):Glycoside(糖苷)Glycoside(糖苷)Monosaccharide(單糖)II.MonosaccharidesGlycosidicbondisunstableunderacidicconditions.(糖苷鍵在酸性條件下不穩(wěn)定)P.19H+ReducingsugarNon-reducingsugar43ChemicalProperties(7):Dehydration5-Hydroxymethylfurfural5-羥甲糠醛Differentfurfuralsreactwithpolyphenolstogeneratedifferentspecificcolors,thereforethisreactionisusefulincharacterizingthemonosaccharides.(用于單糖的定性檢測(cè))II.MonosaccharidesP.2044糠醛-萘酚蒽酚紅紫色縮合物(Molishtest)糠醛藍(lán)綠色復(fù)合物(蒽酚反應(yīng))5-羥甲糠醛鑒定酮糖鑒定戊糖鑒定糖類測(cè)定總糖量糠醛455.ImportantmonosaccharidesandtheirderivativesMonosaccharidesSugarphosphateesters(單糖磷酸酯)Sugaralcohols(糖醇)Sugaracids(糖酸)Sugaresters(糖酯)Sugarethers(糖醚)Deoxysugars(脫氧糖)Aminosugars(氨基糖)Glycosides(糖苷)II.MonosaccharidesP.22Adenosinetriphosphate(ATP)46III.Oligosaccharides(寡糖)Glycosidicbonds(糖苷鍵)Nomenclature(命名)Someoligosaccharides Oligosaccharidearesaccharidesconsistingof2-20monosaccharideunitsjoinedcovalentlybyanO-glycosidicbond.471. Glycosidicbonds(糖苷鍵)Formation:由一個(gè)單糖的異頭碳上的羥基和另一個(gè)單糖的任一個(gè)C上的羥基縮合而成 bycondensationof-OHgroupattheanomericC(異頭碳上的羥基)fromonesugar-OHgroupfromanothersugarReducingend(還原端):

--withafreeanomericCNonreducingend(非還原端)：

--withoutafreeanomericCAnoligosaccharidewitha reducingendisareducing sugar(有還原端的寡糖是還原糖).Stabilityofglycosidicbonds (糖苷鍵的穩(wěn)定性):Hydrolyzedbyacid(被酸水解)Stableinalkalinesolution (對(duì)堿穩(wěn)定)麥芽糖III.OligosaccharidesP.34Reducingend(還原端)Nonreducingend(非還原端)48Maltose（麥芽糖）Glucose--1,4-glucoseCellobiose（纖維二糖）glucose--1,4-glucoseIsomaltose（異麥芽糖)Glucose--1,6-glucoseO--D-glucopyranosyl-(14)-D-glucopyranoseO--D-吡喃葡糖基-(14)-D-吡喃葡糖Glc(14)Glc(14)(16)(14)492.Nomenclature(命名)-乳糖半乳糖-葡萄糖Gal(14)Glc蔗糖葡萄糖-果糖Glc(12)FruFru(21)Glc海藻糖葡萄糖-葡萄糖Glc(11)GlcNonreducingsugarsReducingsugarsO--D-吡喃半乳糖基-(14)--D-吡喃葡糖P.35單糖的縮寫(xiě)見(jiàn)P.31，表1-4503.SomeoligosaccharideexamplesSucrose(蔗糖)：Glc(12)FruLactose(乳糖)：Gal(14)GlcMaltose(麥芽糖)：Glc(14)GlcGentianose(龍膽糖):Glc(16)Glc(12)FruCyclodextrin(環(huán)糊精):P.40 Cyclicstructureformedby6-8glucoseresiduesthrough-1,4-glycosidiclinkageIII.OligosaccharidesP.36-4051Cyclodextrins(環(huán)糊精)(14)-OHatC-6-OHatC-2,C-3HydrophobicInside(內(nèi)部疏水)HydrophilicOutside(外部親水)readilydissolveinwateradsorbhydrophobicmoleculestotoformwater-solubleinclusioncomplexsothattheirchemical/physicalpropertiescanbechanged,e.g.,increasedsolubilityhigherstabilityagainstlight,heatandoxygenwidelyusedasstabilizer,anti-oxidant,emulsifier,solubilityenhancer,etc.52IV.Polysaccharides(多糖)ExistenceClassificationHomopolysaccharides(同多糖)Hetereopolysaccharides(雜多糖)531.ExistenceMostcarbohydratesfoundinnatureoccuraspolysaccharides.Consistingofmorethan20monosaccharides.Molecularweight(分子量)of30000–4x108

ThemostcommonconstituentisD-glucosePolysaccharidesdifferfromeachotherin:Natureofthecomponentmonosaccharides(單糖)Lengthofthechains(鏈長(zhǎng))Typesofthebondslinkingtheunits(糖苷鍵)Degreeofchainbranching(支鏈程度)Nonreducingsugars(非還原糖)Nomutarotation(沒(méi)有變旋現(xiàn)象)Nosweetness(無(wú)甜味)IV.PolysaccharidesP.40542.ClassificationBiologicalsources(生物來(lái)源)Plant,animal,microorganismBiologicalfunctions (生物功能)Storagepolysaccharides(貯存多糖)

e.g.starch(淀粉)Structuralpolysaccharides(結(jié)構(gòu)多糖)

e.g.cellulose(纖維素)InformationcarriersCompositions(組成)Homopolysaccharides(同多糖)Heteropolysaccharides(雜多糖)IV.Polysaccharides553.Homopolysaccharides(同多糖)

Function(功能)PolymerStructure(結(jié)構(gòu))Glycosidicbond(糖苷鍵)Size(No.ofunits)Source(來(lái)源)EnergyStarch(淀粉)Plantsstorage-Amylose(直鏈淀粉)Linear(14)Glc50-5000貯存多糖Amylopectin(支鏈淀粉)Branched(14)Glc(16)GlcUpto106Glycogen(糖原)Branched(14)Glc(16)GlcUpto50000AnimalsStructuralCellulose(纖維素)Linear(14)GlcUpto15000Plants結(jié)構(gòu)多糖Chitin(殼多糖)Linear(14)GlcNAcVerylargeAnimals56Amylose

–long,unbranchedchains–(14)linkageAmylopectin–highlybranched–(14)tojoinsuccessiveglucoseresidues–(16)linkagesatbranchpointsStarch:Amylose&amylopectin

（直鏈淀粉&支鏈淀粉）P.4114Ashortsegmentofamylose(直鏈淀粉)(16)(14)Asegmentofamylopectin(支鏈淀粉)57Amylose（直鏈淀粉）1458Aclusterofamyloseandamylopectin59Amylose&amylopectin(直鏈和支鏈淀粉)Bothhavecoiledhelicalstructuresdueto14linkages(都是螺旋結(jié)構(gòu))BotharecharacterizedbyreactionwithI2(都與I2發(fā)生特征反應(yīng))Amylose(直鏈淀粉)darkblue(深藍(lán)色)Amylopectin(支鏈淀粉)purple(紫色)Bothhaveareducingend(都有一個(gè)還原端)Easilyhydratedbecauseof–OHgroups—readytoformH-bondswithwater(都易于水合，因?yàn)橐着c水形成氫鍵)Ingestedbyhydrolysiswithamylases(淀粉酶水解而被吸收)

Amylasesarecapableofcleavingstarchandglycogen:AmylaseCleavageat(14)linkage-amylase內(nèi)切葡糖苷酶

Randominternalcleavage-amylase外切葡糖苷酶

Cleavagefromnonreducingendtorelease-maltoseP.42Fig.1-2460Cellulose（纖維素）IV.PolysaccharidesP.451461Cellulose(14)linkageFlattenedsheetstructure(片層結(jié)構(gòu))–verystableInterchainandintrachainH-bonds(鏈間/鏈內(nèi)氫鍵)Extremelyresistanttohydrolysis(不易水解)Insolubleinwater(不溶于水)Ingestedonlybyruminantanimals(只能被反芻動(dòng)物吸收):hydrolysisbycellulases(纖維素酶)IV.PolysaccharidesP.46Fig.1-2762Agar(瓊脂):P.49Hemicellulose(半纖維素):P.48Peptidoglycan(肽聚糖):P.51Glycosaminoglycan(糖胺聚糖):P.664.Hetereopolysaccharides（雜多糖）IV.Polysaccharides63Agarose(瓊脂糖)Agar(瓊脂)Agarose(瓊脂糖)Agaropectin(瓊脂膠)IV.PolysaccharidesSepharose(瓊脂糖凝膠)P.49Three-dimensionalstructure:adoublehelixwithathree-foldscrewaxis.Cantakeup99.5%H