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Structure and Function of the Mn Oxygen-Evolving Complex

Mn放氧配合物的结构和功能

基本信息

批准号：
8965156
负责人：
VITTAL YACHANDRA
金额：
$ 35.65万
依托单位：
UNIVERSITY OF CALIF-LAWRENC BERKELEY LAB
依托单位国家：
美国
项目类别：
财政年份：
1997
资助国家：
美国
起止时间：
1997-01-01 至 2019-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8965156
关键词：
Address Aerobic Algae Binding Biological Calcium Catalysis Catalytic Domain Charge Chemical Dynamics Chemical Structure Chemicals Chemistry Complex Couples Crystallography Cyanobacterium Data Data Collection Development Dioxygen Electronics Electrons Environment Enzymes Event Excision Geometry Indium Knowledge Lasers Life Ligands Light Location Manganese Mediating Membrane Proteins Metabolism Metalloproteins Metals Methodology Methods Natural regeneration Nature Oxidation-Reduction Oxygen Peroxides Phase Photochemistry Photons Photosynthetic Complexes Photosystem II Reaction Center Physiologic pulse Physiological Pigments Plants Process Protein Dynamics Proteins Protons Publishing Reaction Research Resolution Roentgen Rays Role Sampling Sampling Studies Series Signal Transduction Site Solutions Source Structure Superoxide Dismutase Superoxides Techniques Temperature Theoretical Studies Time Translating Water X ray diffraction analysis X ray spectroscopy X-Ray Crystallography X-Ray Diffraction absorption base catalase catalyst cryogenics density electronic structure emission spectroscopy free-electron laser geometric structure novel strategies oxidation photosystem II planetary Atmosphere protein complex protein structure public health relevance spectroscopic survey

项目摘要

DESCRIPTION (provided by applicant): Metalloproteins containing manganese in a redox-active role are involved in a variety of physiologically important reactions of dioxygen metabolism. These include, amongst others, a superoxide dismutase that detoxifies superoxide radicals to O2 and peroxide, a catalase that disproportionate peroxide to O2 and H2O, and perhaps the most complex and important, the Mn4CaO5 cluster that is involved in the oxidation of water to dioxygen in photosystem II (PS II), an ~500 kDa multi-subunit membrane protein complex. The water-oxidation reaction in PS II involves removal of four electrons, in a stepwise manner by light-induced oxidation, from two water molecules to produce a molecule of oxygen. PS II and the Mn4CaO5 cluster generate almost all of the dioxygen that supports aerobic life, and it is abundant in the atmosphere because of its constant regeneration by the oxidation of water. The light-induced oxidation of water to dioxygen is one of the most important chemical processes occurring on such a large scale in the biosphere. Although the structure of PS II and the chemistry at the catalytic site have been studied intensively, understanding the sequence in the chemistry at atomic-scale from light absorption to water-oxidation requires a new approach beyond the conventional steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the structure of PS II and the Mn4CaO5 cluster at ambient conditions, while overcoming the severe X-ray damage to the redox active center, is key for deriving the mechanism. The intense and ultra-short femtosecond (fs) X-ray pulses of the LCLS (Linac Coherent Light Source) X-ray free electron laser provide an opportunity to overcome the current limitations of room temperature data collection for biological samples at regular X-ray sources. The fs X-ray pulses allow us to acquire the signal before the sample is destroyed, thus making the light-induced snap-shot study proposed here possible. The objective of this proposal is to study the protein structure and dynamics of PS II with X-ray diffraction, as well as the chemical structure and dynamics of the Mn4CaO5 cluster (charge, spin, and covalency) with X- ray spectroscopy during the light-driven process of PS II. We will combine these time-resolved studies with the study of samples in the steady state using advanced methods of X-ray absorption and emission spectroscopy. These studies have the potential to provide an unprecedented combination of correlated data between the PS II protein, the co-factors, and the Mn4CaO5 cluster, providing the geometric and electronic structure and the changes that occur during the catalytic cycle, all of which are necessary for a complete understanding of the mechanism of water oxidation.