Researchers identified the chemical species present for an iron-based Fischer–Tropsch synthesis catalyst and to image their distribution on the nanoscale. When developed further, this new tool may give chemists the ability to design and tailor catalysts for maximum selectivity and efficiency in a wide range of chemical processes. Read more »
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Reaction-Driven Restructuring of Bimetallic Nanoparticle Catalysts
Researchers have used an ambient-pressure x-ray photoelectron spectroscopy (APXPS) apparatus to demonstrate that bimetallic nanoparticle catalysts can undergo profound structural and chemical changes in response to reactive environments at ambient pressures, thereby opening the way for engineering catalysts with enhanced activity and selectivity. Read more »
Extracellular Proteins Promote Zinc Sulfide Aggregation
Researchers from the ALS, Berkeley Lab’s National Center for Electron Microscopy (NCEM), and Lawrence Livermore National Laboratory analyzed biofilm samples rich in zinc sulfide and dominated by sulfate-reducing bacteria, which were collected from lead–zinc mine waters.
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Particles from Comet 81P/Wild 2 Viewed by ALS Microscopes
NASA’s $200-million, seven-year-long Stardust mission returned to Earth thousands of tiny particles snagged from the coma of comet 81P/Wild 2. Four ALS beamlines and the researchers using them were among the hundreds of scientists and dozens of experimental techniques in facilities around the world that contributed to the preliminary examination of the first samples.
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First Detailed Look at RNA Dicer
Scientists have gotten their first detailed look at the molecular structure of an enzyme that Nature has been using for eons to help silence unwanted genetic messages: Dicer, an enzyme that plays a critical role in a process known as RNA interference.
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Snapshots of Ribozyme Reaction States Reveal Structural Switch
RNA, like protein, can sometimes function as an enzyme (ribozyme) to speed biochemical reaction rates. But how does RNA, a simple polymer, enhance reaction rates by at least a million fold? Researchers obtained the structures of a ribozyme trapped in different states of its catalytic cycle, showing how a change in the RNA conformation governs the reaction mechanism. Read more »
Designing a Novel Globular Protein Fold
A major challenge of computational structural biology has been to create, from scratch, new proteins with heretofore unobserved three-dimensional structures. Researchers have now developed and demonstrated a methodology for protein-structure prediction and design by creating the first artificial globular protein with a novel topology. Significantly, the x-ray structure agreed almost precisely with the structure specified by the computational model. Read more »
ALSNews Vol. 216
Originally published on February 19, 2003. Read more »
The Path of Messenger RNA through the Ribosome
Using x-ray crystallography, researchers directly observed the path of mRNA in the 70S ribosome in Fourier difference maps at 7 Å resolution. Image depicts the view down the crystallographic 4-fold axis of the 70S ribosome-mRNA-tRNA complex, showing the head-to-tail juxtaposition of the model mRNAs (red-orange) between adjacent ribosomes. Read more »
Crosslink Density of Superabsorbent Polymers
Researchers from The Dow Chemical Company teamed with academic colleagues to conduct x-ray spectromicroscopy studies of superabsorbent polymers (SAPs), materials with a wide range of applications, including disposable baby diapers. Dow has been able to use the results to help develop the process technology for a new SAP-manufacturing plant. Read more »