December 2012
Burckhard Seelig, University of Minnesota, Ritimukta Sarangi, SSRL
In recent years, enzymes have gained an important role in industry as cheap and environmentally friendly alternatives to traditional chemical catalysts. Learning to create such enzymes from scratch is necessary in order to provide biocatalysts for the wealth of non-natural reaction chemistries and substrates that have emerged over the last century.
Until now this has been achieved only when extensive knowledge of the mechanism of the reaction is available. Recently, however, researchers have used a clever in vitro strategy to synthesize an artificial RNA ligase enzyme capable of a previously unknown catalytic activity, and to do so they began with a protein not associated with catalysis. A team of scientists led by Burckhard Seelig of the University of Minnesota have now determined the unique structure of this novel biocatalyst using NMR and synchrotron-based Zn K-edge EXAFS at SSRL's Beam Line 9-3
BL9-3
November 2012
Joy C. Andrews (SSRL), Bert M. Weckhuysen (Utrecht)
Olefins are the basic building blocks for many products from the petrochemical industry and are currently produced by steam cracking of naphtha or ethane, but increasing oil and gas prices are driving the industry toward producing olefins from syngas derived from cheaper feedstocks via the Fischer-Tropsch process instead. A team of scientists used full-field Transmission hard X-ray Microscopy (TXM) and a special reactor designed and built at SSRL and installed on SSRL Beam Line 6-2 to learn more about the catalyst at the heart of the Fischer-Tropsch-to-Olefins (FTO) process.
BL6-2
November 2012
T. J. Reber, University of Colorado, D. S. Dessau, University of Colorado
In solids, Fermi surfaces are the boundaries between occupied and unoccupied electron levels, as defined in momentum space. Their properties dictate that each Fermi surface should form a single unbroken loop. To the surprise of physicists, disconnected segments of the Fermi surface – Fermi arcs – were discovered in cuprate superconductors in 1998.
In a study recently published in Nature Physics, researchers from the University of Colorado have used angle-resolved photoemission spectroscopy (ARPES) at SSRL Beam Line 5-4 to determine the origin of these Fermi arcs in the cuprates.
Angle-resolved photoelectron spectroscopy
BL5-4
November 2012
Alessandra Leri, Marymount Manhattan College (aleri@mmm.edu), Satish Myneni, Princeton University (smyneni@princeton.edu)
Recent work at SSRL has helped reveal a previously unrecognized wealth of bromine chemistry in the environment, where bromine in seawater has long been thought to exist as inorganic bromide, while bromides in soil were considered so unreactive that they've routinely been used as a hydrological tracer.
The reality bromine chemistry in the environment is much more complex. X-ray absorption spectroscopic (XAS) studies conducted by Leri, et al. at SSRL Beam Lines 2-3 and 4-3, as well as at the ALS and NSLS, reveal a complicated association between bromine and organic carbon in both sea water and soil.
X-ray Absorption Spectroscopy
BL2-3, BL4-3
October 2012
Corwin Booth, Lawrence Berkeley National Laboratory, Tsu-Chien Weng, SSRL
The structural, electronic, and magnetic properties of U and Pu elements and intermetallics remain poorly understood despite decades of effort, and currently represent an important scientific frontier toward understanding matter. The last decade has seen great progress both due to the discovery of superconductivity in PuCoGa5 and advances in theory that finally can explain fundamental ground state properties in elemental plutonium, such as the phonon dispersion curve, the non-magnetic ground state, and the volume difference between different phases of the pure element.
BL6-2
October 2012
Jeff Gelb, Xradia
Researchers at SSRL, General Motors, Imperial College London, National Taiwan University, and elsewhere have recently begun experimenting with 3-D transmission X-ray microscopy (TXM), in order to gain new insight into the microstructure of battery electrodes.
BL6-2
October 2012
Rongsheng Jin, The Sanford-Burnham Research Institute
Botulinum neurotoxins (BoNTs) invade motor neurons at their junctions with muscular tissue, where the toxins disable the release of the neurotransmitter acetylcholine and subsequently paralyze the affected muscles. Accidental BoNT poisoning primarily occurs through ingestion of food products contaminated by Clostridium botulinum, the bacterium that produces BoNTs. However, BoNTs by themselves are fragile and sensitive to low pH environments and digestive proteases. So how do they survive the harsh environment of the host’s gastrointestinal tract?
Macromolecular Crystallography
BL9-2
September 2012
Irimpan Mathews, SSRL, Amnon Kohen, University of Iowa
Flavin-dependant thymidylate synthases (FDTSs) are a class of recently identified family of thymidylate synthases that employ novel mechanism for the thymidylate synthase reaction. Thymidylate synthases use N5,N10-methylene-5,6,7,8-tetrahydrofolate (CH2H4folate) to reductively methylate 2’-deoxyuridine-5’-monophosphate (dUMP) producing 2’-deoxythymine-5’-monophosphate (dTMP). dTMP is one of the four DNA building blocks and is crucial for survival of all organisms. Unlike other deoxynucleotides, dTMP cannot be directly synthesized by a ribonucleotide reductase, and its de novo biosynthesis requires the enzyme thymidylate synthase. Therefore, inhibition of thymidylate synthesis stops DNA production, arresting cell cycle and eventually leading to “thymineless” cell death. The human enzyme has long been recognized as a target for anticancer drugs.
Since FDTS enzymes are mainly found in very pathogenic microbes including the pathogens causing leprosy, botulism, diarrhea, anthrax, pneumonia, syphilis, etc., the FDTS enzyme is an attractive target for antibiotic drugs.
Macromolecular Crystallography
BL9-2, BL12-2
September 2012
Claudia Y. Janda, Howard Hughes Medical Institute, Stanford University, Christopher Garcia, Howard Hughes Medical Institute, Stanford University
Wnt proteins engage an array of receptors and inhibitors to precisely regulate crucial processes during embryonic development and tissue homeostasis and repair in the adult, and deregulated Wnt signaling is observed in many types of cancers and degenerative diseases.
Macromolecular Crystallography
BL11-1
September 2012
Helen Nichol, University of Saskatchewan, Sam Webb, SSRL
Brain injuries from stroke are both common and costly. The NIH has estimated that the total annual cost of stroke in the United States is $43 billion including direct medical care and the costs related to lost productivity. It has been recognized that rapid diagnosis and treatment is essential to limit neuronal cell death from either a bleed into the brain (hemorrhagic stroke) or a blockage that deprives part of the brain of oxygen (ischemic stroke). The Synchrotron Medical Imaging Team, a group of Canadian, US, and European scientists from diverse backgrounds are collaborating to better understand the underlying chemistry of stroke and how to best image and treat stroke patients.
BL2-3, BL4-3, BL10-2
