NON-CHANNEL FORMS OF GRAMICIDIN IN LIPID MEMBRANE BY DQC ESR

通过 DQC ESR 测定脂膜中非通道形式的短杆菌肽

• 批准号: 8363972
• 负责人: BORIS G DZIKOVSKI
• 金额: $ 0.57万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8363972
• 关键词: Address; Complex; Equilibrium; Fingerprint; Funding; Gel; Gramicidin; Grant; Hand; Head; Label; Left; Lipids; Measures; Membrane Lipids; Minor; Molecular Conformation; National Center for Research Resources; Octanols; Phase; Positioning Attribute; Principal Investigator; Research; Research Infrastructure; Resources; Series; Site; Source; Spin Labels; Structure; System; Technology; United States National Institutes of Health; Work; cost; dimer; gramicidin A; monomer; saturated fat

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In previous work on channel formation using spin labeled Gramicidin A (GAsl) we found that the non-channel form prevails in the gel phase of mismatching lipids (DPPC, DSPC). We have now addressed the assignment of non-channel forms and studied the complex equilibrium in the gramicidin/lipid system, which includes channels (i.e. head-to-head dimers [HHD]), non-channel dimers, and monomers. To study non-channel forms of spin labeled GA, which can aggregate, we labeled two different sites on the same gramicidin molecule, instead of measuring the distance between spin labels attached at the same position on both dimer-forming molecules. This intramolecular distance between the spin labels could be used as a fingerprint of the particular conformation. Interactions between spin labels on different gramicidin molecules were eliminated by substantially diluting the double spin-labeled gramicidin by unlabeled gramicidin. Several new spin labeled gramicidin compounds were synthesized and used. In octanol, gramicidin exists mainly as a double helical (DH) left-handed antiparallel dimer, and we determined interspin distances for this structure. GAD with both N- and C-termini labeled and GALN, single-labeled at the N-terminus, substantially impair their propensity to HHD formation. In most lipids we observed two different conformations of GAD. The interspin distance in the main fraction (20.0¿) is consistent with the monomeric state. Double helices (31.6¿, exactly as in octanol) are a minor component with the fraction changing in the saturated lipid series in the following order: DLPC<DMPC<DSPC<DPPC. We also showed by DQC that both gramicidin monomers and DH exist in all studied lipid phases only in aggregates.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供 该子项目的主要支持。 并且子项目的首席研究员可能是由其他来源提供的， 包括其他 NIH 来源的子项目可能列出的总成本。 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 在之前使用自旋标记短杆菌肽 A (GAsl) 进行通道形成的工作中，我们发现非通道形式在错配脂质（DPPC、DSPC）的凝胶相中占主导地位。短杆菌肽/脂质系统中的复杂平衡，包括通道（即头对头二聚体 [HHD]）、非通道二聚体和单体 研究自旋标记的非通道形式。 GA 可以聚集，我们在同一个短杆菌肽分子上标记了两个不同的位点，而不是测量两个二聚体形成分子上相同位置上附着的自旋标签之间的距离，这种自旋标签之间的分子内距离可以用作指纹。通过用未标记的短杆菌肽充分稀释双自旋标记的短杆菌肽，消除了不同短杆菌肽分子上自旋标记之间的相互作用，并合成了几种新的自旋标记的短杆菌肽化合物。在辛醇中，短杆菌肽主要以双螺旋 (DH) 左手反平行二聚体的形式存在，我们对该结构的 N 端和 C 端均进行了自旋距离测定，而 GALN 则在 N 端进行了单标记。在大多数脂质中，我们观察到主要部分中的两种不同的自旋距离（20.0¿）。 ）与单体状态一致。双螺旋（31.6¿，与辛醇中完全相同）是饱和脂质系列中的次要成分，其分数按以下顺序变化：DLPC<DMPC<DSPC<DPPC。短杆菌肽单体和 DH 仅以聚集体形式存在于所有研究的脂相中。