New Way to Harvest Energy from Sunlight

New Way to Harvest Energy from Sunlight

  9:37:00 AM    Science Lover

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Professor Richard Watt and his chemistry students suspected that a common protein could potentially react with sunlight and harvest its energy -- similar to what chlorophyll does during photosynthesis.

BYU chemistry professor Richard Watt. (Credit: Image courtesy of Brigham Young University)

The story of how they proved it sounds as colorful as the legend of the leprechaun who hid his pot of gold at the end of the rainbow.

They started with citric acid from oranges and mixed it with the protein. Next they dissolved gold powder into the solution. Then they put vials of the yellow-colored mixture in direct sunlight and crossed their fingers in the hope that it would turn purple.

Here's the reason why: If it turned purple, that would signal that the gold atoms had received electrons and used the donated energy to bunch together as small, purple-colored nanoparticles. And that would mean that the protein used the sunlight to excite the citric acid and trigger a transfer of energy.

While direct sunlight did the trick in about 20 minutes, a high-powered tungsten mercury lamp worked much faster.

"We set the system up, turned on the light, and the solution turned purple," Watt said. "We knew that we'd proved the concept."

The beauty of this experiment lies not in its colors -- unless, of course, you're thinking of it as a potential "green" energy source that keeps the environment clean.

The BYU researchers published their experiments in the Journal of Nanoparticle Research. The final step of this project will involve connecting the protein to an electrode to channel the energy into a battery or fuel cell. The BYU chemists will partner with Jae-Woo Kim of the National Institute of Aerospace for this next stage of the work.

Professor Watt's pedigree includes a post-doc at Princeton, a father who developed a fuel cell that runs on sugar and weed-killer and a more distant ancestor credited with inventing the first practical steam engine. That ancestor is also the Scottish engineer for whom the unit of power "watt" is named.

Co-authors on the new study include BYU graduate Jeremiah Keyes, grad student Robert Hilton and Jeff Farrer, who runs an electron microscope lab at BYU.

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Your Body Recycling Itself -- Captured on Film

Your Body Recycling Itself -- Captured on Film

  8:26:00 PM    Science Lover

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Our bodies recycle proteins, the fundamental building blocks that enable cell growth and development. Proteins are made up of a chain of amino acids, and scientists have known since the 1980s that first one in the chain determines the lifetime of a protein. McGill researchers have finally discovered how the cell identifies this first amino acid -- and caught it on camera.

This image shows UBR-box recognition of an arginine residue at the beginning of a protein (blue) targeted for degradation. The structural integrity of the UBR box depends on zinc (grey) and a histidine residue (red) that is mutated in Johanson-Blizzard syndrome. (Credit: Department of Biochemistry, McGill University.)

"There are lots of reasons cells recycle proteins -- fasting, which causes loss of muscle, growth and remodeling during development, and normal turnover as old proteins are replaced to make new ones," explained lead researcher, Dr. Kalle Gehring, from McGill's Department of Biochemistry. "One way that cells decide which proteins to degrade is the presence of a signal known as an N-degron at the start of the protein. By X-ray crystallography, we discovered that the N-degron is recognized by the UBR box, a component of the cells' recycling system."

The powerful technique can pinpoint the exact location of atoms and enabled the team to capture an image of the UBR box, providing insight to this incredibly tiny yet essential part of our bodies' chemical mechanics.

Aside from representing a major advance in our understanding of the life cycle of proteins, the research has important repercussions for Johanson-Blizzard syndrome, a rare disease that causes deformations and mental retardation. This syndrome is caused by a mutation in the UBR box that causes it to lose an essential zinc atom. Better understanding of the structure of the UBR box may help researchers develop treatments for this syndrome.

The research was published in Nature Structural & Molecular Biology and received funding from the Canadian Institutes of Health Research.

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How Spiders Create Silk Threads

How Spiders Create Silk Threads

  5:55:00 PM    Science Lover

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How can a tiny spider body contain material for several decimeters of gossamer silk, and what governs the conversion to thread? Researchers at the Swedish University of Agricultural Sciences (SLU) in Sweden can now explain this process.

Artificial spider silk. (Credit: Image courtesy of 
Swedish University of Agricultural Sciences)

The new research findings are presented in an article in the scientific journal Nature.

"We have seen how the first part of the spider silk protein has a very special and important function. It quite simply controls when the protein is to be converted into gossamer," says My Hedhammar, one of the researchers at SLU.

By rapidly lowering the pH, a spider can initiate the conversion to silk. Before this, the protein needed to form the silk is stored in a gland in the spider's body.

When it is time to spin a thread, the protein passes through a canal where it is converted to gossamer. Along the canal, the conditions change: among other things, the pH is lowered from a neutral (pH 7) to a somewhat more acidic level, pH 6.

"The spider gossamer protein consists of three parts. At SLU, this time we have primarily studied the first part, named NT, and have seen that it has very special properties that are important to the spider. At neutral pH, NT helps the protein to remain in liquid form. When the pH goes down, NT sees to it that threads are formed rapidly and also in an orderly manner," says My Hedhammar.

It has long been a dream of researchers to be able to produce artificial spider silk, since it is one of the strongest materials known. There are therefore great hopes about what spider gossamer could be used for in the future, everything from surgical sutures to bullet-proof vests. Spider silk is a strong and elastic material, and it is moreover biodegradable. It could be of great importance in medical technology, for example.

To be able to produce artificial gossamer, basic research about how spiders go about it is a key piece of the puzzle. Numerous researchers around the world are trying to map this process.

At SLU several scientists are involved in this work, which is largely done with classical biochemical methods. These researchers have primarily conducted their studies using the spider Euprosthenops australis, a species that makes one of the strongest threads and that is moreover large enough to be dissected in a simple way. But the new findings about gossamer protein seems to apply to all spider silk, regardless of species.

The SLU researchers behind the research now presented in the new issue of the journal Nature are Glareh Askarieh, My Hedhammar, Kerstin Nordling, Anna Rising, Jan Johansson, and Stefan D. Knight.

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Peptides May Hold 'Missing Link' to Life

Peptides May Hold 'Missing Link' to Life

  1:47:00 AM    Science Lover

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Emory scientists have discovered that simple peptides can organize into bi-layer membranes. The finding suggests a "missing link" between the pre-biotic Earth's chemical inventory and the organizational scaffolding essential to life.

Researchers tagged one end of peptide chains with an 
NMR label, and then allowed them to assemble to see 
if the ends would interact. The result was a bi-layer 
membrane with inner and outer faces and an additional, 
buried layer that localized functionality within the interior. 
(Credit: Image courtesy of Emory University)

"We've shown that peptides can form the kind of membranes needed to create long-range order," says chemistry graduate student Seth Childers, lead author of the paper recently published by the German Chemical Society's Angewandte Chemie. "What's also interesting is that these peptide membranes may have the potential to function in a complex way, like a protein."

Chemistry graduate student Yan Liang captured images of the peptides as they aggregated into molten globular structures, and self-assembled into bi-layer membranes. The results of that experiment were recently published by the Journal of the American Chemical Society.

"In order to form nuclei, which become the templates for growth, the peptides first repel water," says Liang, who is now an Emory post-doctoral fellow in neuroscience. "Once the peptides form the template, we can now see how they assemble from the outer edges."

In addition to providing clues to the origins of life, the findings may shed light on protein assemblies related to Alzheimer's disease, Type 2 diabetes, and dozens of other serious ailments.

"This is a boon to our understanding of large, structural assemblies of molecules," says Chemistry Chair David Lynn, who helped lead the effort behind both papers, which were collaborations of the departments of chemistry, biology and physics. "We've proved that peptides can organize as bi-layers, and we've generated the first, real-time imaging of the self-assembly process. We can actually watch in real-time as these nano-machines make themselves."

The ability to organize things within compartments and along surfaces underpins all of biology. From the bi-layer phospholipids of cell membranes to information-rich DNA helices, self-assembling arrays define the architecture of life.

But while phospholipids and DNA are complicated molecules, peptides are composed of the simple amino acids that make up proteins. The Miller-Urey experiment demonstrated in 1953 that amino acids were likely to be present on the pre-biotic Earth, opening the question of whether simple peptides could achieve supra-molecular order.

To test how the hollow, tubular structure of peptides is organized, the researchers used specialized solid-state nuclear magnetic resonance (NMR) methods that have been developed at Emory during the past decade. Working with Anil Mehta, a chemistry post-doctoral fellow, Childers tagged one end of peptide chains with an NMR label, and then allowed them to assemble to see if the ends would interact. The result was a bi-layer membrane with inner and outer faces and an additional, buried layer that localized functionality within the interior.

"The peptide membranes combine the long-range structure of cell membranes with the local order of enzymes," Childers said. "Now that we understand that peptide membranes are organized locally like a protein, we want to investigate whether they can function like a protein."

The goal is to direct molecules to perform as catalysts and create long-range order. "We'd really like to understand how to build something from the bottom up," Childers says. "How can we take atoms and make molecules? How can we get molecules that stick together to make nano-machines that will perform specific tasks?"

The research is part of "The Center for Chemical Evolution," a center based at Emory and Georgia Tech, for integrated research, education and public outreach focused on the chemistry that may have led to the origin of life. The National Science Foundation and the U.S. Department of Energy have funded the research.

Many groups studying the origins of life have focused on RNA, which is believed to have pre-dated living cells. But RNA is a much more complicated molecule than a peptide. "Our studies have now shown that, if you just add water, simple peptides access both the physical properties and the long-range molecular order that is critical to the origins of chemical evolution," Childers says.

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