THE ROLE OF CHARGE AND HYDROPHOBICITY IN PEPTIDE LIPID INTERACTION - A COMPARATIVE-STUDY BASED ON TRYPTOPHAN FLUORESCENCE MEASUREMENTS COMBINED WITH THE USE OF AQUEOUS AND HYDROPHOBIC QUENCHERS
THE ROLE OF CHARGE AND HYDROPHOBICITY IN PEPTIDE LIPID INTERACTION - A COMPARATIVE-STUDY BASED ON TRYPTOPHAN FLUORESCENCE MEASUREMENTS COMBINED WITH THE USE OF AQUEOUS AND HYDROPHOBIC QUENCHERS
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DOI：
10.1021/bi00488a006
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发表时间：
1990-09-11
期刊：
影响因子：
2.9
通讯作者：
DEKRUIJFF, B
中科院分区：
文献类型：
--
作者：
DEKROON, AIP;SOEKARJO, MW;DEKRUIJFF, B
摘要：用色氨酸荧光技术研究了相关的模型肽与模型膜的相互作用。所使用的肽是序列H-Ala-Met-Leu-Trp-Ala-OH的衍生物，该序列是为此目的而设计的。几个修改产生了一组13 penta-hexaptidesvary净电荷，疏水性，电荷分布，和色氨酸残基相对于电荷的分子内位置。这些肽的亲和性的小单层囊泡（SUV）组成的两性离子卵磷脂（eggPC）和带负电荷的牛心磷脂（bhCL）的比较方式进行了研究。亲和力的标准包括（1）用脂质囊泡滴定肽后的固有荧光变化，（2）在脂质存在下，肽对色氨酸荧光（L和丙烯酰胺）的水性猝灭剂的可及性降低，以及（3）暴露于膜掺入的荧光猝灭剂溴化磷脂酰胆碱（BrPC）。应用溴化在不同位置沿着酰基链提供的信息的肽的膜拓扑结构。关于对两性离子膜的亲和力的程度，肽的总体疏水性是主要决定因素。携带单个正电荷或负电荷的同样疏水的肽对PC的亲和力的比较揭示了阳离子肽的优先相互作用。疏水和静电相互作用决定了带正电荷的一价和二价肽对CL囊泡的亲和力。在二价带正电荷的肽，无论是在分子的一端或在每一端的带电部分的分布，对这些肽的CL的亲和力几乎没有影响，但影响暴露于BrPC的程度。当通过用增加量的PC稀释CL来降低囊泡的表面电荷密度时，两种类型的肽显示出不同的行为。色氨酸相对于肽分子中带电部分的位置显示出与囊泡相互作用后影响荧光性质。关于膜的拓扑结构，所有的肽采取的定位在膜表面附近，与中性肽插入比chargedpeptides稍微更深的双层。结果允许比较分析的因素确定的程度和模式的脂质模型肽相互作用，此外，所应用的方法的有效性进行了讨论。脂质-肽相互作用在广泛的生物过程中所起的功能作用正获得越来越多的实验支持。例如，越来越多的证据支持信号肽和线粒体前序列与膜脂质的直接相互作用，所述膜脂质在前体蛋白的膜插入或易位过程的某个阶段发挥作用[综述参见Briggs和Gierasch（1986）以及Roise和Schatz（1988）]。此外，已经暗示脂质-肽相互作用催化调节肽与其受体的结合，并且在相关肽（例如阿片肽）的情况下帮助选择适当的受体亚型[综述参见萨金特et al.（1988）]。然而，这些相互作用的基本分子机制的详细知识是缺乏的。
Revised Manuscript Received May 8, 1990 abstract: The interaction of interrelated modelpeptides with model membranes has been studied by techniques based on tryptophan fluorescence. The peptides used are derivatives of the sequence H-Ala-Met-Leu-Trp-Ala-OH, which was designed for this purpose. Several modifications yielded a set of 13 penta-and hexapeptidesvarying in net charge, hydrophobicity, charge distribution, and the intramolecular position of the tryptophan residue with respect to the charge (s). The affinity of these peptides for small unilamellar vesicles (SUV) consisting of zwitterionic egg phosphatidylcholine (eggPC) and negatively charged beef heart cardiolipin (bhCL) has been investigated in a comparative way. The criteria for affinity comprise (1) intrinsic fluorescence changes upon titration of the peptides with the lipid vesicles,(2) reduced accessibility of the peptides to aqueous quenchers of tryptophan fluorescence (L and acrylamide) in the presence of lipid, and (3) exposure to membrane-incorporated fluorescence quenchers, brominated phosphatidylcholines (BrPC). Application of BrPC brominated at different positions along the acyl chains provided information on the membrane topology of the peptides. With respect to the extent of affinity for zwitterionic membranes, the overall hydrophobicity of the peptides is the main determinant. A comparison of the affinity for PC of equally hydrophobic peptides carrying either a single positive or negative charge reveals preferential interaction of the cationic peptide. Both hydrophobic and electrostatic interactions determine the affinity of positively charged mono-and divalent peptides for CL vesicles. The distribution of the charged moieties in divalent positively charged peptides, either both at one end of the molecule or one at each end, has little influence on the affinity of these peptides for CL but does affect the extent of exposure to BrPC. Upon decreasing the surface charge density of the vesicles by diluting CL with increasing amounts of PC, both types of peptides show different behavior. The position of the tryptophan relative to the charged moiety in the peptide molecule is shown to affect the fluorescent properties upon interaction with vesicles. Concerning the membrane topology, all peptides adopt a localization near the membrane surface, with the neutral peptides inserting slightly deeper into the bilayer than the chargedpeptides. The results allow a comparative analysis of the factors determining the extents and modes of lipid-model peptide interaction; in addition, the validity of the methods applied is discussed. e functional role that lipid-peptide interactions play in a wide range of biological processes is acquiring growing ex-perimental support. For example, there is increasing evidence in favor of a direct interaction of signal peptides and of mitochondrial presequences with the membrane lipids playing a role at some stage of the membrane insertion or translocation process of precursor proteins [for review see Briggs and Gierasch (1986) and Roise and Schatz (1988)]. Furthermore, lipid-peptide interactions have been implied to catalyze the binding of regulatory peptides to their receptor and to assist in the selection of the proper receptor subtype in the case of interrelated peptides, eg, the opioid peptides [for review see Sargent et al.(1988)]. Nevertheless, detailed knowledge of the basic molecular mechanisms underlying these interactions is lacking.