February 11, 2006, 3:14 PM CT

Role Of Hydrogen Bonds In Protein Folding

By changing individual atoms in key places in proteins, Duke University chemists have found new evidence for the importance of comparatively weak "hydrogen bonds" in enabling stringlike proteins to fold into the maximally stable shape they need to assume their roles as biological workhorses. Such protein folding immediately after proteins are synthesized is central to their function in the cell.

Eventhough they are much weaker than the preeminent "covalent" chemical bonds that bind atoms in biological molecules, hydrogen bonds are known to occur at key points along the central "backbone" structures of all folded proteins. The hydrogen bonds are created by attractions between adjacent hydrogen and oxygen atoms that are sandwiched into the molecular framework.

How big a role hydrogen bonds actually play in protein folding has been a controversial scientific question, as per Duke associate chemistry professor Michael Fitzgerald. "There's been an ongoing debate about the exact role of those hydrogen bonds," he said in an interview. "Are they really super-important, or are they really negligible?".

Fitzgerald, his graduate student Min Wang and his former graduate student Thomas Wales helped address that question in an effort that took years of work.

One by one, they slightly "mutated" the normal arrangement of atoms in proteins to effectively delete hydrogen bonds at five analogous positions along the structural "backbones" of two different protein molecules that fold in the same pattern. Then they analyzed how each deletion affected the stability of the protein. "Stability" means how low energy, or "relaxed," the protein was.........

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January 28, 2006, 6:25 PM CT

Where's the beef?

Where's the beef? Maybe in your paint can, or in that bottle of nail polish remover. Research at the University of Alberta is giving new meaning to beefing up chemicals and fuels.

Kelly Maher, who is working towards her master of science degree in the U of A Faculty of Agriculture, Forestry and Home Economics, is exploring the possibilities of converting beef tallow - fat - into a liquid similar to those produced using petroleum or fossil fuels. The end product could be used in everyday products like solvents, paint and lacquer.

Traditionally, tallow was a valued product of the rendering industry, but the recent BSE scare resulted in a significant drop in value, from $374 per tonne in 2002 to $242 per tonne in 2003, as per Alberta Agriculture, Food and Rural Development. This undervalued byproduct of the rendering process, which sees almost every other part of an animal's carcass used, would fill an emerging demand from chemical supply companies for biodegradable products, Maher said.

"We live in a fossil-fuel world and there are numerous problems associated with our extensive use of petroleum," Maher said. "There is uncertainty over oil prices, growing environmental concern over fossil fuel combustion and most importantly, our reserves are depleting and will eventually run out. Tallow is a renewable resource that could be sustainable over a long period of time".........

Posted by: Sarah      Permalink


January 28, 2006, 6:06 PM CT

Powering The Planet

Rising populations and living standards will trigger a dramatic increase in global energy consumption over the next 50 years, Professor Nocera told the 320-strong audience at the Energy Futures Lab's special lecture. Because of this, science's greatest challenge is to find secure, sustainable and environmentally responsible ways to meet this demand.

Eventhough dismissing claims that fossil fuels will not be plentiful enough to supply our needs, he warned of the potentially catastrophic environmental consequences of relying on them too heavily.

"The people who claim CO2 in the atmosphere doesn't contribute to global warming are the biggest gamblers and risk-takers you've ever met," he declared, adding: "If I'm wrong, I'm a safe bet - just one more crazy MIT professor, and believe me there are plenty".

Professor Nocera's area of research, and one he believes holds enormous long-term potential for energy creation, is solar power. If photosynthesis can be duplicated outside the leaf, he explained, the sun's energy can be harnessed as a fuel. The combination of water and light from the sun can be used to produce hydrogen and oxygen. The hydrogen can then be combined with the oxygen in a fuel cell to give back water and energy.

There is, however, a catch. Admitting that our scientific know-how is still not advanced enough to enable this technique, he warned his audience: "If you want to buy into me, it will be the worst investment you've ever made in your lives".........

Posted by: Sarah      Permalink


January 25, 2006, 8:54 PM CT

Nano Motor Powered by Solar Energy

Chemists at Italy's University of Bologna, UCLA and the California NanoSystems Institute have designed and constructed a molecular motor of nanometer size that does not consume fuels; their nano motor is powered only by sunlight. The research, federally funded by the National Science Foundation, will be published Jan. 31 in Proceedings of the National Academy of Sciences (PNAS).

The nano motor can work continuously without any external interference, and operates without consuming or generating chemical fuels or waste, said Fraser Stoddart, UCLA's Fred Kavli Professor of NanoSystems Sciences and director of the institute.

"We design and make sunlight-powered nano motors and then 'test drive' them much as an engineer would a new motorcar," Stoddart said. "It is as if we had managed to get a solar-powered motor car onto the road and running".

Precisely how light-powered nano motors will be used in the future is still not clear, Stoddart said, but he listed many possible areas for applications: nanoelectronics, molecular computers and nano valves that perhaps could be used for the delivery of anti-cancer drugs and other medications.

"The achievement reported in PNAS is the culmination of a research effort lasting a quarter of a century and involving hundreds of students and millions of dollars," Stoddart said.........

Posted by: Kevin      Permalink


January 20, 2006, 6:43 AM CT

Managing supplies Of Copper, Zinc

Scientists studying supplies of copper, zinc and other metals have determined that these finite resources, even if recycled, may not meet the needs of the global population forever. As per the study, if all nations were to use the same services enjoyed in developed nations, even the full extraction of metals from the Earth's crust and extensive recycling programs may not meet future demand.

The scientists suggest the environmental and social consequences of metals depletion become clearer from studies of metal stocks--those in the Earth, in use serving people and lost in landfills--instead of tracking the flow of metal through the economy in a given time and region.

Yale University scientists Robert Gordon and Thomas Graedel and their colleague Marlen Bertram of the Organisation of European Aluminum Refiners report their findings in the Jan. 17, 2006, Proceedings of the National Academy of Sciences.

"There is a direct relation between requisite stock, standard of living, and technology in use at a given time," said Gordon. "We therefore offer a different approach to studying use of finite resources, one that is more directly correlation to environmental concerns than are the discussions found in the economics literature".

Using copper stocks in North America as a starting point, the scientists tracked the evolution of copper mining, use and loss during the 20th century. Then the scientists applied their findings, and additional data, to an estimate of global demand for copper and other metals if all nations were fully developed and used modern technologies.........

Posted by: Sarah      Permalink


January 15, 2006, 8:21 PM CT

Probing Combustion Process

Chemists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, working with colleagues at Stony Brook University, have developed a unique experimental technique to measure the flow of energy inside a molecule in the process of breaking apart. The chemists' experiments provide a critical test of theories used in computer models of combustion, which are used, for instance, by combustion engineers to design more fuel-efficient and less polluting machines.

"With a trustworthy computer model of combustion, engineers can design improved engines or fuel blends without needing to build and test so a number of different versions," said Brookhaven chemist Gregory Hall, the principal researcher for this experiment. "The database of chemical reactions needed for such a computer program is too big to be filled in strictly with measured numbers, and we have to rely on chemical rate theory to calculate much of this database. Our experiments are important for showing how far we should trust these calculations."

The Chemical Physics Research Program in DOE's Office of Basic Energy Sciences funded the research, which is due would be published online today in the Journal of Chemical Physics.

The chemists used an experimental technique called "sliced ion imaging" to analyze the energy flow during the fragmentation of ketene, a small molecule that acts as a stand-in for more complicated fuels in these benchmark experiments. When excited with a laser, ketene breaks apart into carbon monoxide and methylene fragments, pushing away from each other with a speed that depends on the rotational and vibrational energies of the two fragment molecules. Some of the carbon monoxide fragments are then ionized (an electron is removed) by a second laser, and the ions are accelerated toward a detector screen, where each ion shows up as a flash of light, observed with a video camera. Depending on how fast and in what direction the carbon monoxide fragments were traveling when they were born, the ions will hit a different spot on the ion-imaging detector. By analyzing the images obtained by accumulating the signals from about half a million molecules, the Brookhaven researchers can determine how energy is shared between the two fragments. They have found agreement with the predictions of a chemical rate theory called variational transition state theory, refuting some earlier work that had raised questions about this theory.........

Posted by: Sarah      Permalink


January 8, 2006, 11:52 AM CT

Supersolid Matter In Making

The scientists at the university of the State of Pennsylvania announce the possible discovery of an entirely new matter phase: a ultra-cold, forms "supersolid" of helium-4.

Writing in a January issue of the nature, the physicist Moise H. W Chan and his graduated student, Eun-Seong Kim of state of Penn, explain why their material is a solid in the sense that all its atoms helium-4 are cold in a rigid crystal trellis, just like the atoms and the molecules in a normal solid such as the ice. The difference is that "frozen," in this case, does not mean "stationary." Since the trellis helium-4 is so much very cold, less than one tenth of a degree above absolute zero, the laws of the uncertainty of quantum succeeds. Indeed, the helium atoms start to behave as if they were solid and fluid in the the same time. In the good circumstances, in fact, a certain fraction of the helium atoms can start to move by the trellis like a substance known under the name of "superfluid": a liquid which moves without friction some. Thus the "named supersolid".........

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December 28, 2005, 11:59 PM CT

Hydrogen Atoms Manipulated

For the first time, researchers have manipulated hydrogen atoms into stable sites beneath the surface of a palladium crystal, creating a structure predicted to be important in metal catalysts, in hydrogen storage, and in fuel cells. The research would be published in the 13 December 2005 issue of the journal Proceedings of the National Academy of Science.

Observations of the effects of the resulting subsurface hydrides--hydrogen atoms with a partial negative charge--confirmed the existence of the stable sites, which had been predicted but previously had neither been deliberately assembled nor directly observed. The research was led by Paul S. Weiss, Distinguished Professor of Chemistry and Physics at Penn State.

After moving absorbed hydrogen atoms to just below the crystal surface, the scientists were able to observe how the presence of the hydride in specific sites within a metal crystal affects the chemical, physical, and electronic properties of the metal. Understanding these effects could advance efforts to improve chemical reactions involving metal catalysts. In addition, the subsurface hydride may provide a model material for application in hydrogen storage and fuel cells. The ability to prepare the subsurface hydride provides an important research tool for these applications.........

Posted by: Sarah      Permalink


December 27, 2005, 9:26 PM CT

This Principle Also Valid For Atoms

In the 16th century Galileo Galilei dropped leaden, golden and wooden objects off the leaning tower in Pisa. He found that all objects reached the ground at the same time. This illustrates the more general result that in a gravitational field the motion of all bodies is the same independent of their mass and composition. Einstein took up this finding to formulate the "equivalence principle" and used it as a key assumption to develop his gravitational theory.

Today, there exist a strong challenge to verify the equivalence principle on an atomic level, since corresponding experiments could provide hints on how gravitational theory and quantum mechanics, two fundamental theories in modern physics, could be combined into a uniform description. German researchers from Garching and Tuebingen have performed a modern version of the "leaning tower" experiment. They tested the equivalence principle for quantum objects in an atomic fountain with an atom interferometer, which is a quantum mechanical device. They compared the Earth's gravitational acceleration for two different rubidium isotopes (Rb-85 and Rb-87) and performed a test of the equivalence principle on an atomic level to an accuracy of two parts in ten millions (Physical Review Letters, Vol. 93, 240404 (2004), 10 December 2004).........

Posted by: Jaison      Permalink


December 25, 2005, 10:02 PM CT

Common Houshold Detergents Good To Remove Lead

All-purpose detergents remove lead-contaminated dust from household surfaces just as effectively as high phosphate detergents and lead-specific cleaning products, according to new research scheduled for publication in the Jan. 15 issue of the American Chemical Society's Environmental Science and Technology journal.

The researchers, led by Roger D. Lewis, Ph.D., CIH, of the Saint Louis University School of Public Health, tested how well various detergents removed lead from three common household surfaces: vinyl flooring, wood and wallpaper. They determined that all-purpose floor detergents containing no phosphate did just as well as a more expensive lead-specific product and trisodium phosphate (TSP), a less environmentally friendly substance. Lead-specific cleaners or TSP have long been recommended for lead removal.

Of the approximately 100 million housing units in the United States, about 24 million have significant levels of lead in dust, soil or paint, according to the U.S. Department of Housing and Urban Development (HUD). New HUD guidelines, to be released in 2006, will incorporate the findings from this research, according to Lewis. The study was funded by HUD's Office of Healthy Homes and Lead Control.........

Jaison      Permalink