生化反應(yīng)之溶劑水課件

Chapter2:BiomoleculesinWater水做為溶劑之特殊性非共價(jià)作用力解離常數(shù)與pH緩衝溶液Chapter2:BiomoleculesinWat水為生物的首選溶劑Biologicalsolvent:amediumformetabolicreactionsaquaporins:membranechannelsforwatertransportEssentialbuffertoregulatetemperatureandpH:highspecificheatcapacityandpH-regulatingsubstancesdissolvedinitParticipantinmanybiochemicalreactions:photosynthesisandhydrolysisofATP水為生物的首選溶劑Biologicalsolvent:a水是威力強(qiáng)大的小分子水是威力強(qiáng)大的小分子WeakChemicalBondsNon-covalentinteractions:Hydrogenbonds氫鍵Ionicinteractions離子交互作用(靜電吸引力)Hydrophobicinteractions(厭水性交互作用)vanderWaalsinteractions(凡得瓦爾力)

這些弱的維繫力重要性何在?*WeakChemicalBondsNon-covalen“Themorecomplexthesystem,theweakeraretheforcesthatgovernitsbehavior”

-J.R.Platt

較強(qiáng)

較弱

Forces:

核間力 原子力共價(jià)鍵 非共價(jià)鍵 重力

_________________________________________

Structure:

原子 核原子簡單化合物生物巨分子宇宙

簡單複雜“Themorecomplexthesystem,TheFourWeakInteractions*共通特質(zhì)：非共價(jià)可逆專一TheFourWeakInteractions*共通特ThePolarNatureofWaterGiventhedifferenceinelectronegativitybetweenoxygenandhydrogen(3.5-2.1=1.4)anditsshape,waterisapolarmoleculewithadipolemomentof1.85Dthenetchargeonoxygenis-0.66andthatoneachhydrogenis+0.33ThePolarNatureofWaterGiven1.HydrogenBonds<5%ofthebondstrengthofaO-H(20vs.460kJ/mole)Muchlongerbonddistance:0.18vs.0.096nmHighlydirectionalBasedonthedipolemomentofwaterAccountfortheunusualpropertiesofwaterasbothsubstanceandsolvent1.HydrogenBonds<5%ofthebCommonHydrogenBonds*PeptidesX-H:::AX=HydrogenbonddonorN,O,SA=HydrogenbondacceptorO,NCommonHydrogenBonds*PeptidesHydrogenbondinginice冰為何浮在水上？Icecrystal:staticWater:dynamicbreakingandformingHydrogenbondinginice冰為何浮在水上重要生物分子間氫鍵重要生物分子間氫鍵HydrogenBondStrengthisHighlyDirectionalFig.2-5

HydrogenBondStrengthisHigh

2.IonicInteractionsTheyareabout5-10%thestrengthofacarbon-carbonbond(20-40vs.350kJ/mole)Ionicallystabilizedcompounds(likeNaCl)arereadilydissolvedinsolventswithahighdielectricconstant(likewater)

Why?F=Q1Q2/er2

e:dielectricconstant r:distancebetweenthechargegroups2.IonicInteractionsTheyareSolventPropertiesofH2OIoniccompounds(e.g.,KCl)andlow-molecular-weightpolarcovalentcompounds(e.g.,C2H5OHandCH3COCH3)tendtodissolveinwaterTheunderlyingprincipleiselectrostaticattractionofunlikecharges;thepositivedipoleofwaterforthenegativedipoleofanothermolecule,etc.ion-dipoleinteraction:e.g.,KCldissolvedinH2Odipole-dipoleinteractions:e.g.,ethanoloracetonedissolvedinH2Odipoleinduced-dipoleinteractions:weakandgenerallydonotleadtosolubilityinwaterSolventPropertiesofH2OIonicDipole-DipoleIon-DipoleDipole-DipoleIon-DipoleSaltsDissolveinAqueous“CagesofHydration”Fig.2-6還有什麼因素讓鹽很容易溶於水？SaltsDissolveinAqueous“Cag氧既是非極性，又如何支持生命？氧既是非極性，又如何支持生命？3.HydrophobicInteractionsTheyareabout2%thestrengthofacarbon-carbonbond(8vs.350kJ/mole)WaterbecomeshighlyorderedaroundhydrophobicgroupsGreasychainsstaytogethertominimizeentropylossbywater3.HydrophobicInteractionsThe生化反應(yīng)之溶劑水課件生化反應(yīng)之溶劑水課件生化反應(yīng)之溶劑水課件水的退出有利酵素與受質(zhì)作用水的退出有利酵素與受質(zhì)作用4.vanderWaalsInteractionsTheyareabout1%thestrengthofacarbon-carbonbond(4vs.350kJ/mole)Attractionbetweenatomsbytransiently-induceddipolesRepulsionwhentheelectroncloudsbumptogether4.vanderWaalsInteractions生化反應(yīng)之溶劑水課件Chapter2:BiomoleculesinWater水做為溶劑之特殊性非共價(jià)作用力解離常數(shù)與pH緩衝溶液Chapter2:BiomoleculesinWat水為生物的首選溶劑Biologicalsolvent:amediumformetabolicreactionsaquaporins:membranechannelsforwatertransportEssentialbuffertoregulatetemperatureandpH:highspecificheatcapacityandpH-regulatingsubstancesdissolvedinitParticipantinmanybiochemicalreactions:photosynthesisandhydrolysisofATP水為生物的首選溶劑Biologicalsolvent:a水是威力強(qiáng)大的小分子水是威力強(qiáng)大的小分子WeakChemicalBondsNon-covalentinteractions:Hydrogenbonds氫鍵Ionicinteractions離子交互作用(靜電吸引力)Hydrophobicinteractions(厭水性交互作用)vanderWaalsinteractions(凡得瓦爾力)

這些弱的維繫力重要性何在?*WeakChemicalBondsNon-covalen“Themorecomplexthesystem,theweakeraretheforcesthatgovernitsbehavior”

-J.R.Platt

較強(qiáng)

較弱

Forces:

核間力 原子力共價(jià)鍵 非共價(jià)鍵 重力

_________________________________________

Structure:

原子 核原子簡單化合物生物巨分子宇宙

簡單複雜“Themorecomplexthesystem,TheFourWeakInteractions*共通特質(zhì)：非共價(jià)可逆專一TheFourWeakInteractions*共通特ThePolarNatureofWaterGiventhedifferenceinelectronegativitybetweenoxygenandhydrogen(3.5-2.1=1.4)anditsshape,waterisapolarmoleculewithadipolemomentof1.85Dthenetchargeonoxygenis-0.66andthatoneachhydrogenis+0.33ThePolarNatureofWaterGiven1.HydrogenBonds<5%ofthebondstrengthofaO-H(20vs.460kJ/mole)Muchlongerbonddistance:0.18vs.0.096nmHighlydirectionalBasedonthedipolemomentofwaterAccountfortheunusualpropertiesofwaterasbothsubstanceandsolvent1.HydrogenBonds<5%ofthebCommonHydrogenBonds*PeptidesX-H:::AX=HydrogenbonddonorN,O,SA=HydrogenbondacceptorO,NCommonHydrogenBonds*PeptidesHydrogenbondinginice冰為何浮在水上？Icecrystal:staticWater:dynamicbreakingandformingHydrogenbondinginice冰為何浮在水上重要生物分子間氫鍵重要生物分子間氫鍵HydrogenBondStrengthisHighlyDirectionalFig.2-5

HydrogenBondStrengthisHigh

2.IonicInteractionsTheyareabout5-10%thestrengthofacarbon-carbonbond(20-40vs.350kJ/mole)Ionicallystabilizedcompounds(likeNaCl)arereadilydissolvedinsolventswithahighdielectricconstant(likewater)

Why?F=Q1Q2/er2

e:dielectricconstant r:distancebetweenthechargegroups2.IonicInteractionsTheyareSolventPropertiesofH2OIoniccompounds(e.g.,KCl)andlow-molecular-weightpolarcovalentcompounds(e.g.,C2H5OHandCH3COCH3)tendtodissolveinwaterTheunderlyingprincipleiselectrostaticattractionofunlikecharges;thepositivedipoleofwaterforthenegativedipoleofanothermolecule,etc.ion-dipoleinteraction:e.g.,KCldissolvedinH2Odipole-dipoleinteractions:e.g.,ethanoloracetonedissolvedinH2Odipoleinduced-dipoleinteractions:weakandgenerallydonotleadtosolubilityinwaterSolvent