Structural and Electron Dynamics of the O-O bond Formation in Photosystem II

光系统 II 中 O-O 键形成的结构和电子动力学

• 批准号: 2004147
• 负责人: Yulia Pushkar
• 金额: $ 45万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2004147&HistoricalAwards=false
• 关键词: Structural; Electron; Dynamics; bond; Formation

With this award, the Chemistry of Life Processes Program of the Chemistry Division is supporting Dr. Yulia Pushkar of the Department of Physics and Astronomy at Purdue University to study the mechanism of dioxygen (O2) formation in the naturally-occurring photosynthetic protein Photosystem II. This protein uses the energy of sunlight to split water molecules into protons, electrons and oxygen molecules, providing the majority of the oxygen in the Earth’s atmosphere. Plants subsequently use the electrons and protons in chemical processes resulting in CO2 fixation. The chemical center of Photosystem II responsible for water-splitting contains manganese and calcium ions, that work together in the crucial chemical catalysis process that sustains our biosphere. Establishing the fundamental mechanism of this process in molecular detail could enable the design of new methods for CO2-neutral sunlight-powered energy production. The planned educational activities focus on increasing opportunities for and the participation in research activities for students from backgrounds underrepresented in STEM careers. Dr. Pushkar advises in research students who participate in the Minority Access to Research Careers and Access Internally for Minorities, the Louise Stokes Alliance for Minority Participation, and Research Experiences for Undergraduate Programs. She also mentors student recipients of Summer Undergraduate Research Fellowships, Discovery Park Undergraduate Research Internships, and the Edward S. Akeley Award and Lijuan Wang Award for Women in Physics and contributes to the training of young women scientists through research and presentations in Purdue’s Women in Physics and Women in Science Programs. Research in this project focuses on the use of laser pump X-ray probe time-resolved X-ray emission, absorption and scattering to study the oxygen-evolving complex (OEC) of Photosystem II, which participates in the O-O bond formation and O2 evolution, the critical step of photosynthesis. The analysis of the electronic structure of the Mn4Ca cluster is conducted with microsecond (µsec) time resolution and the structural changes in the cluster are determined with ~0.02 Å precision. Critical technology developments are made in high-resolution, high-sensitivity X-ray spectrometers, nanoliter drop-on demand sample delivery systems, and biological time-resolved X-ray spectroscopy at newly developed high-flux synchrotron beamlines. The experimental results are interpreted in the framework of currently available structural models of the OEC. Complementary DFT calculations are conducted to monitor the energy profile of the proposed chemical transformations in the OEC. Elucidation of the structural changes in the OEC that accompany the critical catalytic step of O-O bond formation and elucidation of the nature of the species activating water by combined experimental data and DFT modeling are stepping stones for understanding the details of the mechanism of catalytic water-splitting.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.

通过这个奖项，化学部门的生命过程化学项目正在支持普渡大学物理和天文学系的Yulia Pushkar博士研究自然发生的光合蛋白Photosystem II中二氧（O2）形成的机制。这种蛋白质利用太阳光的能量将水分子分解成质子、电子和氧分子，为地球大气提供了大部分氧气。植物随后在化学过程中使用电子和质子，从而固定二氧化碳。光系统II负责水分解的化学中心含有锰离子和钙离子，它们在维持我们生物圈的关键化学催化过程中共同作用。在分子细节上建立这一过程的基本机制，可以设计出二氧化碳中性太阳能发电的新方法。计划中的教育活动侧重于为来自STEM职业中代表性不足的背景的学生增加参与研究活动的机会。Pushkar博士建议参加少数民族研究职业和少数民族内部访问，路易斯斯托克斯少数民族参与联盟和本科项目研究经验的研究学生。她还指导了夏季本科生研究奖学金、探索公园本科生研究实习、爱德华·s·阿克利奖和王丽娟物理学女性奖的学生获得者，并通过普渡大学物理学女性和科学女性项目的研究和演讲，为年轻女科学家的培训做出了贡献。本项目的研究重点是利用激光泵浦x射线探针的时间分辨x射线发射、吸收和散射，研究光系统II中参与光合作用关键步骤O-O键形成和O2演化的氧演化复合物（OEC）。对Mn4Ca簇的电子结构进行了微秒（µsec）时间分辨率的分析，并以~0.02 Å的精度确定了簇中的结构变化。在新开发的高通量同步加速器光束线上，在高分辨率、高灵敏度x射线光谱仪、纳升按需样品递送系统和生物时间分辨x射线光谱学方面取得了关键技术发展。实验结果在现有结构模型的框架下进行了解释。补充的DFT计算被用来监测OEC中所提出的化学转化的能量分布。通过结合实验数据和DFT模型，阐明O-O键形成这一关键催化步骤所伴随的OEC结构变化，以及阐明激活水的物质的性质，是理解催化水裂解机理细节的基石。该奖项反映了美国国家科学基金会的法定使命，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。

项目成果

A Mononuclear Non-heme Iron(III)–Peroxo Complex with an Unprecedented High O–O Stretch and Electrophilic Reactivity

具有前所未有的高 O-O 拉伸和亲电反应性的单核非血红素铁 (III)-过氧复合物

• DOI: 10.1021/jacs.1c03358
• 发表时间: 2021
• 期刊: Journal of the American Chemical Society
• 影响因子: 15
• 作者: Zhu, Wenjuan;Jang, Semin;Xiong, Jin;Ezhov, Roman;Li, Xiao-Xi;Kim, Taeyeon;Seo, Mi Sook;Lee, Yong-Min;Pushkar, Yulia;Sarangi, Ritimukta
• 通讯作者: Sarangi, Ritimukta

Revisit the E2 Domain of Amyloid Precursor Protein: Ferroxidase, Superoxide and Peroxynitrite Scavenging Activities

• DOI: 10.1021/acs.inorgchem.3c01336
• 发表时间: 2023-06-27
• 期刊: INORGANIC CHEMISTRY
• 影响因子: 4.6
• 作者: Poore，Andrew T. T.;Zuercher，Eli C. C.;Tian，Shiliang
• 通讯作者: Tian，Shiliang

A Manganese Compound I Model with a High Reactivity in the Oxidation of Organic Substrates and Water

• DOI: 10.1021/jacs.3c01818
• 发表时间: 2023-04-10
• 期刊: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
• 影响因子: 15
• 作者: Zhang，Lina;Seo，Mi Sook;Nam，Wonwoo
• 通讯作者: Nam，Wonwoo

X-ray Emission Spectroscopy of Single Protein Crystals Yields Insights into Heme Enzyme Intermediates

• DOI: 10.1021/acs.jpclett.2c03018
• 发表时间: 2022-12-25
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY LETTERS
• 影响因子: 5.7
• 作者: Emamian，Sahand;Ireland，Kendra A.;Davis，Katherine M.
• 通讯作者: Davis，Katherine M.