Physical Sciences and Mathematics Commons^™

Structure And Function Of Cytochrome Containing Electron Transport Chain Proteins From Anoxygenic Photosynthetic Bacteria, Erica Lois-Wunderlich Majumder

Arts & Sciences Electronic Theses and Dissertations

This dissertation examines the structure and function of photosynthetic proteins that contain c-type heme cofactors that function in the electron transport chains of anaerobic phototrophic bacteria. The diversity and range of these cytochromes proteins was explored. Then, individual proteins were studied in detail. The diheme cytochrome c from Heliobacteria modesticaldum was studied using hydrogen deuterium exchange mass spectrometry and homology modeling. A structural model of the protein and a mechanism for the cytochrome bc complex was proposed. Next, the monoheme cytochrome c subunit from the Alternative Complex III from the Filamentous Anoxygenic Phototrophs was studied using biochemistry and found to …

Engineering Photosystem I Complexes For Use In Bio-Hybrid Dye-Sensitized Solar Cells, Richard Franklin Simmerman

Doctoral Dissertations

Increasing global population, growing per capita energy needs, diminishing fossil fuels, and climate change collectively will require new, innovative, and sustainable alternatives to meet the world’s growing energy needs. One of the most promising yet simple approaches are dye-sensitized solar cells (DSSCs). However, conventional DSSCs use semi-conductor anodes sensitized with complex synthetic organometallic dyes. Most dyes utilize ruthenium complexes to absorb photons, which upon excitation, inject electrons into the anode, while holes migrate to the cathode via liquid electrolyte. However, these dyes are expensive, difficult to make, and resource-limited. This dissertation focuses on replacing synthetic dyes with the naturally occurring, …

Light-Harvesting, Redox Control, And Biomimicry Of The Photosynthetic Antennas Of Green Sulfur Bacteria, Gregory Scott Orf

Arts & Sciences Electronic Theses and Dissertations

The green sulfur bacteria (class Chlorobea) are obligately anaerobic photoautotrophic prokaryotes. Members of this bacterial class are found in anoxic, sulfur- or iron-rich environments such as hydrothermal vents and hot springs. These bacteria are champions of lowlight adaptation, with some species being able to thrive photosynthetically on less than eight photons hr-1 per pigment. We have studied the two photosynthetic antenna complexes from these organisms that are responsible for light capture: the chlorosome and the Fenna-Matthews-Olson (FMO) protein.

In regards to the chlorosome, we studied, using steady-state and time-resolved spectroscopic methods, the effect of incorporation of an expected, but as-yet-undiscovered-in-nature, …

Productivity, Absorbed Photosynthetically Active Radiation, And Light Use Efficiency In Crops: Implications For Remote Sensing Of Crop Primary Production, Anatoly A. Gitelson, Yi Peng, Timothy J. Arkebauer, Andrew E. Suyker

School of Natural Resources: Faculty Publications

Vegetation productivity metrics such as gross primary production (GPP) at the canopy scale are greatly affected by the efficiency of using absorbed radiation for photosynthesis, or light use efficiency (LUE). Thus, close investigation of the relationships between canopy GPP and photosynthetically active radiation absorbed by vegetation is the basis for quantification of LUE. We used multiyear observations over irrigated and rainfed contrasting C3 (soybean) and C4 (maize) crops having different physiology, leaf structure, and canopy architecture to establish the relationships between canopy GPP and radiation absorbed by vegetation and quantify LUE. Although multiple LUE definitions are reported in the literature, …

De Novo Design And Engineering Of Functional Metal And Porphyrin-Binding Protein Domains, Bernard Howard Everson

Dissertations, Theses, and Capstone Projects

In this work, I describe an approach to the rational, iterative design and characterization of two functional cofactor-binding protein domains. First, a hybrid computational/experimental method was developed with the aim of algorithmically generating a suite of porphyrin-binding protein sequences with minimal mutual sequence information. This method was explored by generating libraries of sequences, which were then expressed and evaluated for function. One successful sequence is shown to bind a variety of porphyrin-like cofactors, and exhibits light- activated electron transfer in mixed hemin:chlorin e6 and hemin:Zn(II)-protoporphyrin IX complexes. These results imply that many sophisticated functions such as cofactor binding and electron …

Vibrational Spectroscopy Of Photosystem I, Gary Hastings

Physics and Astronomy Faculty Publications

Fourier transform infrared difference spectroscopy (FTIR DS) has beenwidely used to study the structural details of electron transfer cofactors (and their binding sites) in many types of photosynthetic protein complexes. This review focuses in particular onwork that has been done to investigate the A1 cofactor in photosystemI photosynthetic reaction centers. A reviewof this subject area last appeared in 2006 [1], so onlywork undertaken since then will be covered here. Following light excitation of intact photosystem I particles the P700+A1 \ secondary radical pair state is formed within 100 ps. This state decays within 300 ns at room temperature, or 300 …

Understanding Ocean Acidification Impacts On Organismal To Ecological Scales, Andreas J. Andersson, David I. Kline, Peter J. Edmunds, Stephen D. Archer, Nina Bednarsek, Robert C. Carpenter, Meg Chadsey, Philip Goldstein, Andrea G. Grottoli, Thomas P. Hurst, Andrew L. King, Janet E. Kübler, Ilsa B. Kuffner, Katherine R.M. Mackey, Bruce A. Menge, Adina Paytan, Ulf Riebesell, Astrid Schnetzer, Mark E. Warner, Richard C. Zimmerman

OES Faculty Publications

Ocean acidification (OA) research seeks to understand how marine ecosystems and global elemental cycles will respond to changes in seawater carbonate chemistry in combination with other environmental perturbations such as warming, eutrophication, and deoxygenation. Here, we discuss the effectiveness and limitations of current research approaches used to address this goal. A diverse combination of approaches is essential to decipher the consequences of OA to marine organisms, communities, and ecosystems. Consequently, the benefits and limitations of each approach must be considered carefully. Major research challenges involve experimentally addressing the effects of OA in the context of large natural variability in seawater …

Divergent Responses Of Atlantic Coastal And Oceanic Synechococcus To Iron Limitation, Katherine R. M. Mackey, Anton F. Post, Matthew R. Mcilvin, Gregory A. Cutter, Seth G. John, Mak A. Saito

OES Faculty Publications

Marine Synechococcus are some of the most diverse and ubiquitous phytoplankton, and iron (Fe) is an essential micronutrient that limits productivity in many parts of the ocean. To investigate how coastal and oceanic Atlantic Synechococcus strains acclimate to Fe availability, we compared the growth, photophysiology, and quantitative proteomics of two Synechococcus strains from different Fe regimes. Synechococcus strain WH8102, from a region in the southern Sargasso Sea that receives substantial dust deposition, showed impaired growth and photophysiology as Fe declined, yet used few acclimation responses. Coastal WH8020, from the dynamic, seasonally variable New England shelf, displayed a multitiered, hierarchical cascade …

Predicting Carbon Isotope Discrimination In Eelgrass (Zostera Marina L.) From The Environmental Parameters- Light, Flow, And [Dic], Meredith L. Mcpherson, Richard C. Zimmerman, Victoria J. Hill

OES Faculty Publications

Isotopic discrimination against ¹³C during photosynthesis is determined by a combination of environmental conditions and physiological mechanisms that control delivery of CO₂ to RUBISCO. This study investigated the effects of light, flow, dissolved inorganic carbon (DIC) concentration, and its speciation, on photosynthetic carbon assimilation of Zostera marinaL. (eelgrass) using a combination of laboratory experiments and theoretical calculations leading to a mechanistic understanding of environmental conditions that influence leaf carbon uptake and determine leaf stable carbon isotope signatures δ¹³C. Photosynthesis was saturated with respect to flow at low velocity ~ 3 cm s^-1, but …