RUI: Protein Tyrosine Oxidations to Maintain Cellular Redox State

有了这个奖项，化学部的生命过程化学项目资助了卡尔文学院的大卫·本森博士，研究一些蛋白质如何以及为什么成为抗氧化剂。抗氧化剂，在各种有营养价值的食物中，是被氧化的小分子，而不是细胞成分，如蛋白质、膜或DNA。一类新的抗氧化剂——被修饰成含有抗氧化剂的蛋白质，同时仍然附着在蛋白质上——显著地减少了被修饰蛋白质的氧化。实验程序将详细说明这些蛋白质修饰如何形成和功能，通过使用各种生化，紫外吸收，荧光和质谱检测方法，最大限度地减少对自身或其他蛋白质的氧添加。这项工作将在卡尔文学院和大急流城社区学院对本科生进行培训的同时进行，培训他们如何进行研究，为在高技能的技术劳动力中工作做准备。这项工作的发现将有助于更好地理解生物系统的复原力，同时也为下一代科学工作者做好准备。这项工作将集中在酪氨酸翻译后修饰，可以在生理条件下可逆氧化。众所周知，这些修饰的酪氨酸参与氧化还原催化。一种修饰的酪氨酸，3'-（s-半胱氨酸）-酪氨酸（Cys-Tyr），将在肠道细菌（脆弱拟杆菌）的空气耐受性中进行研究，最小化蛋白质氧化，调节细胞半胱氨酸浓度（大鼠半胱氨酸二氧合酶），并可能调节蛋白质的泛素化。最近开发的荧光分析将用于快速确定在各种条件下的Cys-Tyr反应产率，并将蛋白质功能的变化与Cys-Tyr的形成联系起来。由于Cys-Tyr和其他修饰的酪氨酸表现出可逆的氧化化学反应，因此可以建立Cys-Tyr具有抗氧化作用的假设。这一作用很重要，因为共价连接将抗氧化功能定位到蛋白质上，并在氧化应激反应中提供了一种新的蛋白质功能。

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. David Benson from Calvin College to investigate how and why some proteins become antioxidants. Antioxidants, in a variety of nutritionally valuable foods, are small molecules that get oxidized rather than cellular components such as proteins, membranes, or DNA. A new class of antioxidants-proteins modified to contain antioxidants while still being attached to the protein-dramatically decreases the oxidation of the modified protein. The experimental procedures will detail how these protein modifications form and function in minimizing oxygen addition to themselves or other proteins by using a variety of biochemical, ultraviolet absorbance, fluorescence, and mass spectrometric detection methods. This work will be performed while training undergraduates, at Calvin College and Grand Rapids Community College, on how to perform research in preparation for working in a highly skilled technical workforce. The findings of this work will contribute to better understanding the resilience of biological systems while also preparing the next generation of the scientific workforce.This work will focus on tyrosine post-translational modifications that can be reversibly oxidized under physiological conditions. These modified tyrosines are best known to participate in redox catalysis. The role of one modified tyrosine, 3'-(S-cysteinyl)-tyrosine (Cys-Tyr), will be studied in aerotolerance of a gut bacterium (Bacteroides fragilis), minimizing protein oxidation of a protein that regulates cellular cysteine concentrations (rat cysteine dioxyngease), and potentially modulating ubiquitination of proteins. A recently developed fluorescence assay will be used to rapidly determine Cys-Tyr reaction yield under a variety of conditions and correlate changes in protein function with Cys-Tyr formation. Due to the reversible oxidation chemistry displayed by Cys-Tyr, and other modified tyrosines, the hypothesis is that an anti-oxidant role for Cys-Tyr may be established. This role would be important as covalent-attachment localizes anti-oxidant function to a protein and provides a new protein function in response to oxidative stress.