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时间:2020-03-26
《多肽诱导的巨型脂质体出芽和泄露行为.pdf》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、物理化学学~z(WuliHuaxueXuebao)OctoberActa.一Chim.Sin.2015,31(10),1985—19901985[Article]doi:10.3866/PKU.WHXB201508262www.whxb.pku,edu.CI1多肽诱导的巨型脂质体出芽和泄露行为孙建波夏玉琼于秋红梁德海f北京大学化学与分子工程学院,北京分子科学国家实验室,北京100871)摘要:细胞膜与膜蛋白之间的相互作用与生命中许多过程息息相关.以巨型脂质体(GUV)和多肽分别作为细胞膜和膜蛋白的简化模型,我们设计了四种仅包
2、含亮氨酸(L)和赖氨酸(K)的多肽。即K(KLKLK)、(KLKL)2和K6,并对比研究了它们与中性和负电性脂质体的相互作用.电荷密度最高的K只是涂层在脂质体表面,不破其囊泡结构,但能够引起负电性脂质体发生微相分离,属建设性相互作用.能够形成两亲性a螺旋的(KLKLK)~U(KLKL。)2J几4引起脂质体发生泄露和破裂,属破坏性作用.但二者引起泄露的速率在中性脂质体和负电性脂质体中的结果恰好相反,说明泄露分两步进行:表面吸附多肽达到一定浓度,继而对膜进行干扰.表面活性剂型多肽KBL。的氨基酸组成与(KLKLK)相同,但L8只
3、是引起负电性脂质体发生泄露,造成中性脂质体发生外出芽.这些简单氨基酸造成的脂质体的复杂构象变化可以统一用静电和疏水相互作用在膜上的位置和强度来进行解释.这些结论对于深入理解膜蛋白的作用机理是有帮助的.关键词:多肽:巨型脂质体;出芽:泄露中图分类号:0648Peptide—InducedBuddingandLeakageBehaviorofGiantVesiclesSUNJian-BoXlAYu—QiongYUQiu-HongLIANGDe—Hal’(BeijingNationalLaboratoryforMolecularS
4、ciences,CollegeofChemistryandMolecularEngineering,PekingUniversityBeo'ing100871,P.R.China)Abstract:Theinteractionsbetweenmembraneproteinsandcelfmembranesarecriticalinmanylifeprocesses.Giantunilamellarvesicles(GUVs1andpeptidesaresimplebuteffectivemodelsofmembranesan
5、dmembraneproteins,respectively.Here。wedesignedfourpeptidescomposedoflysine(K)andleucine(L)aminoacids,K(KL2KL2K)2,(KL2KL3)2,andK6L8,andexaminedtheirinteractionswithneutralandnegativelychargedGUVs.ThepeptideK14hasthelargestchargedensityandisabletocoattheGUVsurfacewit
6、houtdamagingitsstructure.Whereas,leakageisobservedinbothneutralandchargedGUYsinthepresenceof(KL2KL2K)2and(KL2KL3)2,whichcanf0rmamphiphilica-helicesinhydrophobicenvironments.However,theleakageratesasafunctionofpeptideconcentrationarereversedfortheneutraIandchargedGU
7、Vs.Thus,leakageOccursintwosteps:absorptionofpeptidesonthesurfaceuptoacertainlevel。folowedbydisruptionofthemembrane.ThepeptideKeLehasthesamechemicalcompositionas(KL2KL2K)2,butinducesleakageonlyonnegativelychargedGUVs,whileneutralGUVsundergooutwardbudding.Conformatio
8、nalchangesofGUVsinducedbysimplepeptidescanbeattributedtotheworkingIocationfonthesurfaceorinsidethemembrane),andthestrengthofelectrostaticandhydro
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