EFRC 501 - Fall 2013

The Bisfuel Center and the Department of Chemistry and Biochemistry continue supporting the graduate class EFRC 501. Graduate students whoa are affiliated with the EFRC are required to take the course. Interdisciplinary collaboration is in the heart of our Center. The class helps the graduate students to see how their research fits into the big picture of the Center, and learn how their work can benefit from the efforts of others.

Time: 12:00 – 1:15 pm

Location: All classes will be held in ISTB5-151 

Schedule of the class:

Date Speaker Title of the talk (linked to abstract) Faculty
Aug 27   Organizational meeting Ana Moore
Sep 3 Marely Tejeda Synthesis of Functionalized Photosensitizer and IrOx nanoparticles for Photoeletrochemical Solar Cell Ryan Trovitch
Sep 10 Shobeir Mazinani Molecular polarizability: A simple tool to estimate electron transfer rates Ana Moore
Sep 17 Reza Vatan  A molecular conductance model for proton coupled electron transfer Kevin Redding
Sep 24 Chelsea Brown Synthesis of high-potential porphyrins and a water oxidation catalyst Thomas Moore
Oct 1 Seyed Ebrahim Hashemi Amiri Incorporation of dye molecules in zeolites via ion exchange Don Seo
Oct 1 Daniel Mieritz Synthesis and Characterization of Transparent, Nanoporous Thin Films of ZrxTi1-xO2 for Energy Applications Don Seo
Oct 8 Justin Flory Nucleic Acid (PNA-DNA) driven Polypeptide Assembly for building an Artificial Oxygen Evolving Complex Giovanna Ghirlanda
Oct 8 Dong Wang Towards water oxidation catalysts Giovanna Ghirlanda
Oct 22 Dayn Sommer A Retrosynthetic Approach to Hydrogen Production: Modeling the Hydrogenase Enzyme. Electron Transfer and Photosensitization Devens Gust
Oct 22 Rafael Alcala-Torano A Retrosynthetic Approach to Hydrogen Production: Modeling the Hydrogenase Enzyme. Catalysis by Active Site Mimics Devens Gust
Oct 29 Joe Laureanti Determining reaction mechanisms utilizing spectroelectrochemical methods Anne Jones
Oct 29 Anna Beiler Electrochemical Characterization of Proteins via Unnatural Amino Acids Anne Jones
Nov 5 Shatabdi Roy-Chowdhury Growing macro and micro crystals of Photosystem-I Yan Liu
Nov 5 Chelsie Conrad Femtosecond Technique Development of Viscous Sample Delivery and Snapshot Diffraction by Mixing Yan Liu
Nov 12 Robert Schmitz Photophysics of a Chemically-Polymerized Porphyrin Polymer Thomas Moore
Nov 12 Ian Pahk Mimicking Photoprotection in a Model Photosynthetic Reaction Center Thomas Moore
Nov 26 Tufan Mukhopadhyay Homogeneous Manganese Catalysts: An effort towards CO2 reduction Hao Yan
Dec 3 Christopher Kupitz Time Resolved Femtosecond Nanocrystallography of PSII Petra Fromme
Dec 3 Shibom Basu Time Resolved Femtosecond Nanocrystallography of PSII Petra Fromme

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ABSTRACTS of the presentations

September 4:

Marely Tejeda

Synthesis of Functionalized Photosensitizer and IrOx nanoparticles for Photoeletrochemical Solar Cell

Abstract: In response to the emergent need for alternative energy sources, artificial photosynthesis has become an important research area. From the hydrolysis of water, photoelectrochemical solar cells can produce hydrogen gas, which can be stored and used as fuel.  The cell consists of 2 components: one side, where the water oxidation occurs, is inspired by photosystem II (PSII) and needs high potential, blue absorbing dyes to drive the oxidation of water by a catalyst, such as IrOx nanoparticles. The other side is a proton reduction component, which needs low potential, red absorbing dyes. The synthesis of high potential porphyrins and IrOx nanoparticles will be presented. The nanoparticles will be capped with azido-acetic acid, which provides the azide moiety that will undergo a further click chemistry reaction with a porphyrin. The dyes will have a terminal triple bond for the reaction with the nanoparticles. The performance of different dyes on the photoelectrochemical solar cell will also be presented.

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September 10:

Shobeir Mazinani

Molecular polarizability: A simple tool to estimate electron transfer rates

Abstract:

Electron transfer (ET) forms the crux of biological redox energetics of chloroplasts and mitochondria. Understanding the nature of electron transfer and estimating the electron transfer rates across biological molecules is therefore an area of intense research.

Theoretical efforts to obtain electron transfer rates have largely relied on Marcus theory. However, an alternative approach based on the proportionality of molecular conductance at low bias and the electron transfer rates, enables us to obtain reliable estimates of electron transfer rates from calculations of molecular conductance. In this work, we explore a hitherto unknown connection between the static molecular polarizability and the molecular conductance. The connection arises in the context of modeling tunneling through barriers including image charge and dielectric effects.

This simple model relating molecular conductance and polarizability, and the proportionality of the former to the electron transfer rates, allows us to predict the rate of electron transfer across hitherto unknown systems from calculations of molecular polarizability.

In the second part of my talk, I will briefly mention on how electronic structure calculations have shed more light on the mechanism of a hydrogenase-inspired [Ni-Fe] complex.

 

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September 17:

Reza Vatan Meidanshahi

A molecular conductance model for proton coupled electron transfer

Abstract:

Under some simplifying assumptions electron transfer (ET) rates and molecular conductance are proportional to each other. We have used this relationship to estimate the effect of chemical substitution, charging and spin multiplicity on the ET rate of a number of reactions that are signicant for the study of proton-coupled electron transfer (PCET). We have also explored a connection between the static molecular polarizability and the molecular conductance that arises in the context of modeling tunneling through barriers including image charge and dielectric effects.

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September 24:

Chelsea Brown

Synthesis of high-potential porphyrins and a water oxidation catalyst

Abstract:

The search for an alternative fuel source has become a worldwide project. Current research focuses on artificial photosynthesis because it is a natural way of using sunlight to convert water, an abundant resource, into oxygen and hydrogen gas. Hydrogen is a storable fuel, which, when burned, produces water. Hydrogen fuel is a zero emission fuel and is entirely renewable. The design of a cell for artificial photosynthesis requires two components, working simultaneously, to oxidize water and to produce hydrogen gas. This project focuses on the water oxidation component of the photoelectrochemical cell. The photoanode requires a high potential, blue-absorbing porphyrin attached to tin oxide and subsequently attached to the water oxidation catalyst. The synthesis of the high-potential porphyrin and the water oxidation catalyst for this construct will be discussed in the first part of the talk. The second part of the talk will discuss the development of a new material that may allow for hole injections into its valence band using a high-potential porphyrin. The synthesis of the high-potential porphyrin for hole injections will be presented.

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October 1:

Seyed Ebrahim Hashemi Amiri

Incorporation of dye molecules in zeolites via ion exchange

Abstract:

From the efforts to mimic a natural photosynthesis in the form of an optoelectronic device, a number of recent attempts have beenmade to improve device performance by the arrangement of fluorescence molecules using various methods. One of the approaches is enclosing fluorescence molecules inside a porous material and by choosing conditions suchthat the cavities are able to accommodate only monomers but not aggregates. Among these porous materials, zeolite is known the suitable hosts for specific organization of chromophores, which is inorganiccrystalline aluminosilicates with pores in nanometer size (typically 0.4-0.8 nm), because of their well-defined internal structure with uniform cages, cavities or channels. Dye molecules as the guest species can be inserted into the channels of zeolite either by ion exchange or by adsorption from the gas. The main focus of the talk will be devoted to an overview on determining the actual cation exchange capacity (CEC) of zeolites as an important factor for Manipulation of Energy Transfer in dye molecule-containing zeolites

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October 1:

Daniel Mieritz

Synthesis and Characterization of Transparent, Nanoporous Thin Films of ZrxTi1-xO2 for Energy Applications

Abstract:

As renewable energy is increasingly important to our future energy security, harnessing solar power is becoming the focus of intense worldwide research with TiO2 as a key material in many solar energy applications. Toward this goal, we have synthesized high surface area, mesoporous TiO2 and Zr-doped TiO2 (ZTO) with sol-gel based chemistry tailored for thin film applications.  Applying a nanoporous thin film increases the specific surface area of a substrate, and exposes more active adsorption sites.  The porous films are employed in solar energy applications including photocatalysis and dye-sensitized solar cells (DSSCs).   Our protocol for synthesis of thin mesoporous films employs polymeric sacrificial gel template formed in situ. In this one-pot synthetic method, both inorganic and polymer precursors are first dissolved in an ethanol/water solvent.  By controlling the synthetic parameters, interpenetrating gel networks of hydrous ZTO and resorcinol-formaldehyde (R/F) polymer were formed in the solution, where the continuity of the inorganic gel component was ensured.  Subsequent drying and calcination  of the inorganic/polymer hybrid gels afforded monolithic mesoporous TiO2 products. For thin film synthesis, the sol was doctor-bladed onto an FTO substrate during gelation.  Transparent and robust films were produced with pore volumes up to ~0.24 cm3/g, specific surface areas as high as ~140 m2/g and pore widths of ~ 5 nm.  Zr loading of 30 at% increased the band gap from 3.27 to 3.61 eV.  Strategies such as pyrolysis before calcination, using different solvents, and using different monomers have shown further potential for controlling the pore characteristics.

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October 8:

Justin Flory

PNA-Polypeptide Assembly in a 3D DNA Nanocage for Building an Artificial Oxygen Evolving Complex

Abstract:

The Photosystem II (PSII) reaction center-pigment-protein complexes catalyze the oxidation of water to produce all the oxygen in the Earth’s atmosphere and enable conversion of solar energy to bioenergy for the entire biosphere. Under full sunlight the native PSII complexes are damaged every 30 minutes due to the accompanying chlorophyll-based photochemistry, which diverts significant resources from biomass production to PSII repair. The Oxygen Evolving Complex (OEC) may be able to function independently of the PSII complex when reconstructed in a more stable environment. Our goal is to assemble the peptides coordinating the metal cluster that catalyzes the water oxidation reaction inside an engineered 3D DNA nanocage.


Here we report modifications to a previously described 3D DNA nanocage design1 to incorporate several test peptides through hybridization with a Peptide Nucleic Acid2 (PNA) linker attached to each peptide. The PNA-peptides hybridized to the preassembled DNA cage at room temperature and could be assembled in a stepwise fashion.3 A PNA linker was also used to introduce Azurin (pI 5.7) and Cytochrome C (pI 10.0) to investigate the affect of polypeptide length and charge on PNA assembly and the redox chemistry inside the DNA cage. Both PNA-proteins hybridize rapidly to the DNA cage and Cytochrome C maintains redox activity while in the DNA cage. These results demonstrate the benign PNA assembly conditions are ideal for preserving higher order polypeptide structure and function. This method will facilitate the peptide-based assembly of an artificial OEC inside a stable DNA nanocage.

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October 8:

Dong Wang

Towards water oxidation catalysts

Abstract:

Artificial photosynthesis is a promising approach for renewable energy production. It aims either to split water (H2O H2 + O2) or reduce carbon dioxide (2CO2 + 4H2O → 2CH3OH + 3O2). Central to both schemes is water oxidation (2H2O → O2 + 4H+ + 4e-). Thus achieving efficient, robust and cheap water oxidation catalyst (WOC) is in demand. We discovered that solution mixture of Ni2+ and certain small molecule showed an enhanced anodic peak in cyclic voltammetry measurement, which we assigned to water oxidation. To elucidate the role of the small molecule in this system, we tested analogues of glycine to mix with Ni2+, the initial result showed that the primary amine group associating with the observed water oxidation peak. Oxygen measurement using oxygen sensor and gas chromatography is under way to verify the producing of oxygen. We are also working on resolving the mechanism of this water oxidation catalyst.

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October 22:

Dayn Sommer

A Retrosynthetic Approach to Hydrogen Production: Modeling the Hydrogenase Enzyme. Electron Transfer and Photosensitization

Abstract:

In the field of bioenergetics, a number of proteins that catalyze energy-relevant reactions utilize varied metallocenters as prosthetic groups. These groups may function for electron transfer within the protein, catalytic centers, or as photosensitizers for the protein. Utilizing de novo design and Solid Phase Peptide Synthesis, the Domain Swap Dimer (DSD) peptide has been engineered to bind two [4Fe-4S] clusters, the first example of a peptide binding two iron-sulfur clusters at once. Current work focuses on binding an alternate version of the [4Fe-4S] cluster, the [3Fe-4S] cluster. The initial characterization of the [3Fe-4S] peptide has shown an α-helical structure that is highly stable to temperature and chemical denaturants. Preliminary attempts to bind [3Fe-4S] clusters have indicated binding of a cluster, confirmed by EPR spectroscopy. Concurrent work on the DSD scaffold aims to utilize an artificial bipyridine amino acid to ligate metals into a trimeric DSD structure. Synthesized bipyridine-DSD will be characterized for metal binding strength as well as photosensitizing abilities. Concepts elucidated from these studies will be applied to design of an artificial hydrogenase enzyme, used for production of H2 for fuel generation.

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October 22:

Rafael Alcala-Torano

A Retrosynthetic Approach to Hydrogen Production: Modeling the Hydrogenase Enzyme. Catalysis by Active Site Mimics

Abstract:

The increasing need for new renewable energy sources has led to the on-going search of environment friendly fuels such as hydrogen. In nature, hydrogenases catalyze the reversible reduction of protons to hydrogen; hence several mimics of these enzymes have emerged in order to achieve the cost-effective production of this gas. The active site of [FeFe]-hydrogenases consists of a diiron cluster containing the non-proteinaceous ligands CO and CN- and a bridging azaditholate moiety, NH(CH2S-)2. Previously, diiron hexacarbonyl was anchored to a single helix peptide scaffold using an artificial amino acid bearing a propanedithiolate moiety producing an active mimic for hydrogenase. Recent work by Berggren et al. has shown that the presence of nitrogen as the bridging atom is necessary for proton reduction in a reconstituted apo hydrogenase. In order to improve the previous single helix model, this work pretends to incorporate Fe2(CO)6 into a peptide scaffold via an azadithiolate ligand and evaluate its hydrogen production activity as well as its electrochemical properties.

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October 29:

Joe Laureanti

Determining reaction mechanisms utilizing spectroelectrochemical methods

Abstract:

Protein film electrochemistry has proven invaluable as a tool to unravel the mechanistic details of complex redox enzymes. However, electrochemistry alone cannot provide structural information, and many energetically important redox enzymes have proven resistant to widespread graphite-based methods of immobilization. This presentation will discuss attempts to use reduced graphene oxysulfide (RGOS) as a substrate for immobilization of proteins at electrode surfaces. RGOS has the advantage over traditional alkylthiol monolayers that it is conductive. Thus it may be possible to use it as a platform for development of new spectroelectrochemical methods.

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October 29:

Anna Beiler

Electrochemical Characterization of Proteins via Unnatural Amino Acids

Abstract:

Unnatural amino acids have successfully been introduced into a protein by use of an amber codon and a specific lab-modified transfer tRNA:aminoacyl-tRNA-synthetase pair using Escherichia coli, and the resultant unique chemical functionality is being exploited to attach the protein to a functionalized carbon electrode. Specifically, an unnatural amino acid with a tyrosine derivate bearing and acetyl moiety, para-acetylphenylalanine (PAcF), is introduced through a point mutation using a variation of the Gibson Assembly approach. Gibson Assembly is traditionally used in cloning but this work demonstrates that it can be easily used in point mutations as well. The electrode is then designed to bear O-hydroxylamine to allow for the condensation of the ketone and hydroxylamine resulting in oxime formation.  Not only will this allow for the electrochemical characterization of a redox protein, but it also allows for specific orientation of the protein, allowing control of electron transfer efficiency between the active site and the electrode. By introducing the mutations at various points along the protein, the dependence of the electron transfer on the orientation of the protein can be analyzed. Currently this method is being used to study plant-type ferredoxin fromSynechocystis PCC 6803, a small soluble 2Fe-2S protein that, among other things, serves as an electron donor to the flavoprotein that reduces NADP+ in the final step of the light-driven reactions of photosynthesis. Following this proof-of-concept, our method can be applied to effectively characterize electron transfer in other proteins.

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November 5:

Shatabdi Roy-Chowdhury

Growing macro and micro crystals of Photosystem-I

Abstract:

With a molecular mass of 360 kDa per monomer, PSI is the largest membrane protein complex with a known structure[1]. The functional protein is a trimer with 12 protein subunits, 96 chlorophyll a molecules, 22 carotenoids, 3 [4Fe4S] clusters, 4 lipid molecules, 2 phylloquinones and a Ca2+ ion per monomer. Primarily, the complex catalyzes light-induced electron transfer from plastocyanin to ferredoxin from the lumenal to the stromal side of the membrane, respectively. Thus, Photosystem-I fixes sunlight to produce chemically useful molecules, making it an important complex to understand for harnessing the solar energy effectively.

X-ray crystallography is the most effective and established method for elucidating three-dimensional structure of macromolecules. Since the first protein structure was solved, the field has made major advances, and yet, producing large, well-ordered crystals still requires extensive experimentation, which can span years to decades for proteins that are difficult to crystallize. With the advent of free electron lasers, it is now possible to explore novel targets using femtosecond crystallography[2]. Because of its extremely robust nature, PSI has served as the model protein for the first nano-crystallography studies using free-electron lasers[4]. But, the concept is relatively new and needs considerable progress, before it can be widely applied.

Combining the positives and negatives of both conventional and nano-crystallography, our goal is to resolve high-resolution structures of the membrane protein complex, in order to answer structurally relevant questions.

References:

  1. Jordan P., Fromme P. et.al, Three-dimensional structure of cyanobacterial photosystem I at 2.5 Å resolution, Nature 411, 909-917 (21 June 2001)
  2. Chapman H. N. et al., Femtosecond X-ray protein nanocrystallography. Nature 470, 73- U81 (2011).
  3. Fromme P. and Grotjohann I., Chapter: Crystallization of photosynthetic membrane proteins, Current Topics in Membranes vol 63, Burlington: Academic Press, pp. 191-227 (2009)
  4. Hunter M.S., Fromme P. et.al, Toward structure determination using membrane-protein nanocrystals and microcrystals, Methods, 55, Issue 4, Pages 387–404, Membrane Protein Technologies for Structural Biology (2011)
  5. Neutze R. et.al, Potential for biomolecular imaging with femtosecond X-ray pulses, Nature, 406, pages 752-757 (2000)

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November 5:

Chelsie Conrad

Femtosecond Technique Development of Viscous Sample Delivery and Snapshot Diffraction by Mixing

Abstract:

Serial femtosecond crystallography (SFX) is a relatively new structural biology technique that is based on femtosecond pulse X-ray diffraction data collection from nano- and microcrystals via free electron lasers (FEL), allowing for challenging protein structures to be solved from tiny crystals at room temperature. Traditional crystallography exposes large crystals to large doses of X-rays causing radiation damage to the crystal and thereby an inaccurate structure. In the SFX technique, microcrystals are delivered in a liquid jet to a X-FEL, producing a diffraction pattern immediately before the crystals are destroyed, resulting in minimal radiation damage. Because samples are not immobilized or frozen in SFX, determination of conformational changes in space and time by induction of the conformational changes “on the fly” is possible. Fast mixing of two liquids, such as enzyme and substrate, immediately before being exposed to the X-ray beam would allow conformational changes to be seen by snapshot diffraction. These snapshots can then be pieced together to form a “molecular movie” of a proteins molecular motions. SFX experiments currently have relied on a liquid jet, delivering sample in the mother liquor focused into a stream by compressed gas. However, this liquid stream moves at a fast rate only allowing approximately every 1 out of 10,000 crystals to be probed by the X-ray beam, meaning that most of the valuable sample is wasted. This work aims to further develop SFX by use of mixing-induced time resolved measurements and an inert, viscous media that would allow for sample limited protein crystals to be probed by SFX.

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November 12:

Robert Schmitz

Photophysics of a Chemically-Polymerized Porphyrin Polymer

Abstract:

A novel method of synthesizing porphyrin polymers via a palladium-catalyzed Buchwald-Hartwig aryl amination of aniline-bearing porphyrins has been developed. The 5-(4-aminophenyl)-15-bromo-10,20-bis(2,4,6-trimethylphenyl)porphyrin monomerunits were coupled into linear chains of porphyrin units linked by aminophenyl groups. The polymer was characterized and then studied via steady-state and time-resolved spectroscopy to understand its photophysical properties. Models of the terminal and bulk units of the polymer were synthesized and oligomers were separated and studied to aid in the deduction of the photophysical activity of the polymer. The steady-state and time-resolved studies indicate that two stable conformations are present in the ground state and that the polymer appears to form an intramolecular charge transfer (ICT) state shortly after excitation which lives for 5 ns. Future studies will incorporate this polymer into bulk heterojunction solar cells.

 

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November 12:

Ian Pahk

Mimicking Photoprotection in a Model Photosynthetic Reaction Center

Abstract:

Photosynthetic organisms employ antenna arrays composed of many chromophore molecules to capture solar energy and funnel it into photosynthetic reaction centers. This energy is used to generate electrochemical potential in the form of a pH gradient across the photosynthetic membrane. As the intensity of incident light increases, the pH on the lumenal side of this membrane decreases. Under strong light conditions there is considerably more solar energy being absorbed than the photosynthetic apparatus can utilize. Unchecked, this would lead to a build up of reactive and potentially harmful redox intermediates within the apparatus. A photoprotective mechanism, nonphotochemical quenching (NPQ), is activated as the pH in the lumen decreases and harmlessly dissipates the excess absorbed energy as heat. Due to the inherent complexity of natural systems, the fundamental mechanistic details of NPQ are not well understood. By studying synthetic analogs we hope to gain insight into the photophysics and photochemistry of NPQ. These artificial systems may also serve as a framework for incorporating photoprotection into organic solar energy devices.

We have designed and synthesized compounds to mimic various aspects of NPQ for photophysical characterization. Our studies of an antenna analog, Hexad, demonstrated the capacity for a pH-sensitive rhodamine dye, R, to rapidly quench zinc porphyrin excited states in an acidified solution1. A reaction center model, Triad, should be able to generate a long-lived charge separated state via photoinduced electron transfer from the excited state of a zinc porphyrin to a functionalized fullerene under neutral conditions. Acidified solutions of Triad are expected to exhibit reduced quantum yields of this charge separated state as excitation energy will be largely dissipated by R.

References:

1. Terazono, Y.; et al. Journal of the American Chemical Society, 2011, 133 (9), 2916-2922.

 

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November 26:

Tufan Mukhopadhyay

Homogeneous Manganese Catalysts: An effort towards CO2 reduction

Abstract:

It has been a major challenge to humanity to develop alternative renewable energy sources. Utilization of naturally available resources has been a very tempting solution for the energy production. For example water oxidation, proton reduction, and carbon dioxide reduction are the viable approaches that can lead to the chemical energy storage. Although, CO2 is highly abundant in atmosphere, at the same time, it is very stable and inert small molecule. Various efforts have been reported in the scientific literature regarding CO2 activation and its reduction to liquid fuels where, transition metal catalysts were found to have an important role.

            Herein, we report the development of homogeneous manganese complexes supported by redox non-innocent ligands. These complexes turned out to be excellent catalysts for the reduction of ketones and esters. Noting the fact that, these manganese complexes can cleave the acyl C-O bond of esters presumably by a radical mechanism, it was thought that these complexes could be suitable precursor for CO2 activation. This presentation will include the isolation, characterization and an understanding of CO2 activation products.

 

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December 3:

Christopher Kupitz and Shibom Basu

Time Resolved Femtosecond Nanocrystallography of PSII

Abstract:

Membrane proteins are extremely difficult to crystallize.  Large, well-ordered crystal growth is a major time constraint in determining structure via x-ray crystallography, currently the most prolific technique.  With the development of femtosecond nanocrystallography (SFX), which uses a stream of fully hydrated nanocrystals to collect diffraction snapshots, this bottleneck is effectively reduced.

Photosystem II changed our biosphere by splitting water and evolving oxygen 2.5 billion years ago.  We are developing the method of time-resolved femtosecond crystallography to unravel the mechanism of water splitting by determining the conformational changes that take place during the oxygen evolution process.  In this presentation we will present the various techniques we have used to grow crystals of the proper size for nanocrystallography, a difficulty because prior to 4 years ago no one even knew crystals of these sizes existed.  The crystals once grown need to be characterized using optical microscopy, dynamic light scattering (DLS), and Second Order Nonlinear Imaging of Chiral Crystals (SONICC) to ensure that they are suitable for use with Serial Femtosecond X-ray crystallography (SFX).  Following characterization, the process of how we collect diffraction patterns and what goes into the technique of SFX will be explained. 

Following the collection of the data, novel techniques, for data analysis, need to be developed to handle the new data.  In this presentation, following the various crystallization techniques, we will talk about methods to analyze millions of diffraction patterns which were collected at the LCLS, SLAC, the world’s first hard X-ray laser, during Jan’2012 beamtime. We will also show our results from that beamtime and recent findings, regarding S1->S3 transition of Oxygen Evolving Complex (OEC). We will talk about the conformational change, observed upon S1->S3 transition, which is consistent with the spectroscopic and computational models of OEC.

References:

  1. Chapman, H.N. et al. Femtosecond X-ray protein nanocrystallography. Nature 470, 73-7(2011)
  2. Umena, Y. et al. Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9Å.  Nature 473,  (2011)
  3. Fromme, P. Grotjohann, I. Structure of Photosystems I and II. Probl. Cell. Differ. 45, 33-72(2008)
  4. Boutet, et al. High Resolution Protein Structure Determination by Serial Femtosecond Nanocrystallography. Science Express, 2012

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