Surface Plasmon-coupled Fluorescence Microscope to Study Ion Channel Dynamics

表面等离子体耦合荧光显微镜研究离子通道动力学

• 批准号: 7084336
• 负责人: FRANCISCO J BEZANILLA
• 金额: $ 18.67万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7084336
• 关键词: bioengineering /biomedical engineering; bioimaging /biomedical imaging; biomedical equipment development; cell line; conformation; cysteine; fluorescence microscopy; fluorescent dye /probe; ionophores; membrane channels; membrane proteins; molecular /cellular imaging; potassium channel; protein structure function; sodium channel; structural biology; surface plasmon resonance; voltage gated channel

DESCRIPTION (provided by applicant): The long term objective of this project is the development of an optical detection system based on surface plasmon resonance to study the dynamics of membrane proteins with special emphasis in voltage gated ion channels such as the Na and K channels that are responsible for the generation and propagation of the nerve impulse. Channel proteins are labeled in specific sites with fluorescent probes using cysteine chemistry and the fluorescence is detected by the proposed optical setup. Fluorescence changes, produced by quenching or energy transfer are indicators of local environmental changes and thus they follow conformational changes within the protein as the channel undergoes transitions from the closed to the open state. The optical apparatus uses a hemispherical lens that couples an incoming laser beam on a glass chip that has a thin (50 nm) siver layer where the biological preparation lies separated by a thin (10 nm) layer of silicon oxide. The correct angle of excitation induces plasmon resonance in the metal and enhances the fluorescence of fluorophores labeling the channel. The detection is done from the biological preparation side or from the excitation side. In the second case the signal to noise ratio is expected to be much larger because the coupled emission comes from a region limited to 20 nm and, as it is directional, a specially designed optics collects most of the light on a photodetector. The testing of the optical sytem is done on labeled ion channels expressed in mammalian cells or in supported bilayers. In the second case, the supported bilayer is made with liposomes containing purified labeled channels. The voltage across the bilayer is changed taking advantage of the silver layer of the plasmon chip. A modification of the optical system is also proposed to image the biological preparation to follow the time course of the fluorescence of individual molecules in response to voltage pulses that change the conformation of the channel. The understanding of conformational dynamics of channel proteins is a crucial step in the design of drugs or therapies needed to ameliorate or cure several neurological deseases produced by abnormal function of ion channels. The optical system developed in this application is aimed at developing a new microscope that is especially designed to detect conformational changes of ion channels with improved resolution, higher sensitivity and improved rejection of spurious fluorescence than presently available devices.

描述（由申请人提供）：本项目的长期目标是开发基于表面等离子体共振的光学检测系统，以研究膜蛋白的动力学，特别强调电压门控离子通道，如负责神经冲动产生和传播的Na和K通道。通道蛋白标记在特定的网站与荧光探针使用半胱氨酸化学和荧光检测所提出的光学设置。由猝灭或能量转移产生的荧光变化是局部环境变化的指标，因此它们随着通道从封闭状态转变为开放状态而跟随蛋白质内的构象变化。该光学装置使用半球形透镜，该透镜将入射激光束耦合到玻璃芯片上，该玻璃芯片具有薄（50 nm）银层，其中生物制剂被薄（10 nm）氧化硅层隔开。正确的激发角度诱导金属中的等离子体共振，并增强标记通道的荧光团的荧光。从生物制剂侧或从激发侧进行检测。在第二种情况下，预期信噪比要大得多，因为耦合发射来自限于20 nm的区域，并且由于它是定向的，因此专门设计的光学器件将大部分光收集在光电检测器上。光学系统的测试是在哺乳动物细胞或支持的双层中表达的标记离子通道上进行的。在第二种情况下，用含有纯化的标记通道的脂质体制备支持的双层。利用等离子体激元芯片的银层来改变跨双层的电压。还提出了一种修改的光学系统的图像的生物制剂，以遵循响应于改变通道的构象的电压脉冲的单个分子的荧光的时间过程。对离子通道蛋白构象动力学的理解是设计改善或治疗由离子通道功能异常引起的神经系统疾病所需的药物或疗法的关键步骤。在本申请中开发的光学系统旨在开发一种新的显微镜，该显微镜特别设计用于检测离子通道的构象变化，与目前可用的装置相比具有改进的分辨率、更高的灵敏度和改进的假荧光抑制。