The Role of Salt Bridges on Gas Phase Protein Structures

化学部的化学测量和成像计划支持加州大学洛杉矶分校（UCLA）的Rachele Loo和Joseph Loo教授。随着生物技术和制药领域对开发治疗性蛋白质药物的兴趣日益增长，了解大生物分子的确切结构的需求正在扩大。尽管人们对该领域的兴趣日益浓厚，但对蛋白质和/或蛋白质复合物的结构如何决定测量的基本理解仍然存在很大差距。这项研究旨在通过详细说明测量本身如何改变蛋白质或蛋白质复合物来填补这一知识空白。质谱（MS）技术用于分析对制药和生物技术行业很重要的生物样品。这项工作的更广泛影响包括提供对医学疾病研究很重要的蛋白质结构的基础知识。 研究小组为南洛杉矶的高级高中生设计化学分析实验室？生物技术职业途径计划。该课程将学生暴露在生命科学的职业生涯中，并提供在生物技术，医学和政府监管机构中使用的可行的STEM相关领域的技术技能。通过监测气相复合物的电荷状态依赖性激活和解离行为，解决了离子对（盐桥）对电喷雾电离（ESI）-MS提供的气相蛋白质和蛋白质复合物的稳定程度。有相当多的证据表明，在ESI中并非所有相反的电荷都被中和;因此，有限的活化可以将带负电荷的侧链重新定向到与阳离子位点相互作用的适当位置，取代溶剂分子“胶水”，从而用盐桥稳定亚基界面。本研究的目标包括展示可以操纵对ESI产生的离子的相反电荷贡献的方法。 该项目还测试模型预测的趋势;例如，对气相截面的影响，对碰撞诱导的气相组件解离产生的产物和电荷态分布的影响，以及对本质无序蛋白质的气相和溶液相结构之间的关系的影响。该研究测试了在ESI-MS中观察到的依赖于电荷态的激活和解离行为是否反映了库仑排斥如何使高电荷态物种不稳定。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Chemical Measurement and Imaging Program in the Division of Chemistry, supports Professors Rachele Loo and Joseph Loo at the University of California-Los Angeles (UCLA). With growing interest in biotech and pharmaceutical fields to develop therapeutic protein-based drugs, the need to understand the exact structures of large biomolecules is expanding. Despite the growing interest in this field, there remains a large gap in the fundamental understanding of how the structure of a protein and/or protein complex dictates the measurements. This research seeks to fill this knowledge gap by detailing how making the measurement itself can change the protein or protein complex. Mass spectrometry (MS) techniques are used to analyze biological samples that are important to the pharmaceutical and biotechnology industries. The broader impacts of this work include providing fundamental knowledge of protein structure that are important to disease research in medicine. The research team designs chemical analysis laboratories for advanced high school students in South Los Angeles? Biotech Career Pathways Program. This program exposes students to life science careers and provides technical skills in viable STEM related fields used in biotechnology, medicine, and government regulatory agencies.The extent of stabilization that ion pairs (salt bridges) provide to gas phase proteins and protein complexes delivered by electrospray ionization (ESI)-MS is addressed by monitoring the charge state-dependent activation and dissociation behaviors of gas-phase complexes. Considerable evidence exists that not all opposing charges are neutralized in ESI; therefore, limited activation can reorient negatively charged side chains into positions well-placed to interact with cationic sites, replacing solvent molecule "glue" formerly stabilizing subunit interfaces with salt bridges. The goals of this research include demonstrating the means by which the opposite charge contributions to ESI-generated ions can be manipulated. The project also tests trends predicted by models; e.g., effects on gas phase cross-sections, on the products and charge-state distributions arising from collision induced dissociation of gas phase assemblies, and on the relationship between gas and solution phase structures of intrinsically-disordered proteins. The investigations test whether the charge state-dependent activation and dissociation behaviors observed in ESI-MS reflect how Coulomb repulsion destabilizes high charge state species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.