This study presents the crystal structure of a thiol variant of the human mitochondrial branched-chain aminotransferase protein. Human branched-chain aminotransferase (hBCAT) catalyzes the transamination of the branched-chain amino acids leucine, valine and isoleucine and α-ketoglutarate to their respective α-keto acids and glutamate. hBCAT activity is regulated by a CXXC center located approximately 10 Å from the active site. This redox-active center facilitates recycling between the reduced and oxidized states, representing hBCAT in its active and inactive forms, respectively. Site-directed mutagenesis of the redox sensor (Cys315) results in a significant loss of activity, with no loss of activity reported on the mutation of the resolving cysteine (Cys318), which allows the reversible formation of a disulfide bond between Cys315 and Cys318. The crystal structure of the oxidized form of the C318A variant was used to better understand the contributions of the individual cysteines and their oxidation states. The structure reveals the modified CXXC center in a conformation similar to that in the oxidized wild type, supporting the notion that its regulatory mechanism depends on switching the Cys315 side chain between active and inactive conformations. Moreover, the structure reveals conformational differences in the N-terminal and inter-domain region that may correlate with the inactivated state of the CXXC center.

The crystal structure of MgCoGa2 (magnesium cobalt digallide) was solved by direct methods and refined in two space groups as P21/c (standard choice) and P21/n (non-standard choice). The refined lattice parameters for the standard choice are a = 5.1505 (2), b = 7.2571 (2), c = 8.0264 (3) Å and β = 125.571 (3)°, and for the non-standard choice are a = 5.1505 (2), b = 7.2571 (2), c = 6.5464 (2) Å and β = 94.217 (3)°. All parameters for MgCoGa2 refined to R1 = 0.027 and wR2 = 0.042 using 594 reflections. The crystal structure peculiarities of this compound are discussed. Particular attention has been given to relationships with other similar structures, such as YPd2Si and Fe3C. Crystallographic analysis, together with linear muffin-tin orbital electronic structure calculations, reveals the presence of three-dimensional polyatomic nets with partial covalent bonding between the Ga atoms.

Describing his project of counting bears, bobcats and other predatory mammals along the Appalachian Trail, National Zoological Park wildlife ecologist William McShea looks to American literature for a comparison.

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When songwriter Oscar Hammerstein penned the lyrics “fish gotta swim, birds gotta fly,” he clearly did not have the ratites in mind. Large flightless birds, the ratites include ostriches, emus, rheas and cassowaries, along with kiwis and several extinct species.

The post DNA evidence is rearranging the branches of the avian family tree appeared first on Smithsonian Insider.

While studying bats recently at the Academy of Natural Sciences in Philadelphia, Smithsonian mammalogist Kristofer Helgen discovered a new species of flying fox bat from […]

The post Smithsonian Scientist Discovers Two New Bat Species Hiding in Museum Collections for More Than 150 Years appeared first on Smithsonian Insider.

A new Smithsonian study that examines 10 million years of the evolution of tiny coral-like organisms called cupuladriid bryzoans has revealed that some species of this organism lingered on earth for more than one million years after the event that ultimately caused their extinction: the rising of the Isthmus of Panama.

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Already under siege from overfishing, disease and poor water quality, the oyster population in the Chesapeake Bay today stands at 2 percent of what it was in colonial times. Now, new data show that rising acidity in the Bay will have a negative impact on oyster shells.

The post Rising acidification of estuary waters spells trouble for Chesapeake Bay oysters appeared first on Smithsonian Insider.

The giant squid was collected during a 60-day scientific study in which NOAA scientists were studying the availability and diversity of sperm whale prey. The squid was caught in a trawl net pulled behind a research vessel at a depth of more than 1,500 feet.

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Scientists from the Smithsonian Migratory Bird Center at the National Zoo have taken blood samples from thousands of birds and mosquitoes in an effort to track the progress of the West Nile Virus in the eastern United States. Come along in this video as Smithsonian scientists net birds living in downtown Washington, D.C., extract small amounts of blood, and then release them back into the "wild."

The post Video: Common birds in Washington, D.C. are helping Smithsonian scientists track intensity of the West Nile Virus appeared first on Smithsonian Insider.

The John Marshall Ju/'hoan Bushman Film and Video Collection, 1950-2000, was among 35 documentary heritage items of exceptional value added to UNESCO’s Memory of the World Register in 2009.

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Native to Africa and Madagascar, females of the species have a body length of 1.5 inches and a leg span of 4 to 5 inches. Males are tiny in comparison.

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Nearly 100 years ago, scientists detected the first signs of cosmic rays—subatomic particles (mostly protons) that zip through space at nearly the speed of light. […]

The post Telescope array finds new evidence that exploding stars are sources of cosmic rays appeared first on Smithsonian Insider.

“Spinning under the influence” is one way to describe recent activities in the Costa Rican laboratory of Smithsonian scientist William Eberhard. An entomologist at the Smithsonian’s Tropical Research Institute, Eberhard recently carried out a series of experiments in which he observed the web-building behavior of dozens of spiders under the influence of drugs—specifically, a chemical injected into their bodies by parasitic wasps.

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A meteorite that crashed through the roof of a Lorton, Va., doctors’ office on Monday, Jan. 18, 2010 was recently identified by scientists in the […]

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Eleven bats remain in the National Zoo’s colony. The initial challenge the team faced was how to feed the animals. Virginia big-eared bats, which are a subspecies of the Townsend’s big-eared bat (Corynorhinuss townsendii), eat while flying.

The post Captive colony of Virginia big-eared bats providing valuable lessons in battle against deadly white-nose syndrome appeared first on Smithsonian Insider.

When it comes to brains, is bigger better? Can the tiny brain of a newly hatched spiderling handle problems as adeptly as the brain of a larger adult spider?

The post Tiny, new brains prove just as adept as large, mature brains among tropical orb-web spiders appeared first on Smithsonian Insider.

This innovative facility will be at the front line of Earth defense by searching for "killer" asteroids and comets. It will map large portions of the sky nightly, making it an efficient sleuth for not just asteroids but also supernovae and other variable objects.

The post Super sensitive telescope will detect “killer” asteroids and comets on collision course with Earth appeared first on Smithsonian Insider.

To understand the effects of road salting on ants, Michael Kaspari of the Smithsonian Tropical Research Institute and the University of Oklahoma led a team that looked at how ant colonies are affected by these conditions; their research is published in a recent issue of the journal Ecological Entomology.

The post Study reveals road salt may promote health and well-being of roadside ant colonies appeared first on Smithsonian Insider.

The Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) PS1 telescope has discovered an asteroid about 150 feet in diameter that will come within 4 million miles of Earth in mid-October.

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Darwin's bark spider cast giant webs across streams, rivers and lakes, suspending the web’s orb above water and attaching it to plants on each riverbank. Bridgelines of these water-spanning webs have been measured as long as 25 meters.

The post Newly discovered Madagascar spider spins largest, toughest webs on record appeared first on Smithsonian Insider.

A new computer simulation by Gurtina Besla of the Harvard-Smithsonian Center for Astrophysics and her colleagues now shows that the Magellanic Stream resulted from a past close encounter between two dwarf galaxies rather than effects of the Milky Way.

The post Milky Way sidelined in galactic tug of war appeared first on Smithsonian Insider.

A roundup of recent articles featuring spiders, bats and rats....

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The Scarlet Knight, as the glider is called, made nautical history as the first submersible glider to successfully cross the Atlantic Ocean.

The post Rutgers glider added to the collections of the National Museum of Natural History appeared first on Smithsonian Insider.

Smithsonian Tropical Research Institute community ecologist Sunshine Van Bael primarily examines the relationship between leaf cutter ants–the world’s first farmers–and the fungi that they cultivate.

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Office of Public Affairs videographers Johnny Gibbons and Brian Ireley recently headed down to the Punta Culebra Nature Center on the edge of Panama City […]

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A recent experiment by scientists at the Smithsonian Tropical Research Institute in Panama has revealed just how rising atmospheric carbon dioxide will deliver a one-two […]

The post Rising ocean temperatures and acidity may deliver deadly one-two punch to the world’s corals appeared first on Smithsonian Insider.

To honor Harvard-Smithsonian astronomer John Huchra, who passed away in October 2010, his friends and colleagues at the Harvard-Smithsonian Center for Astrophysics have created a […]

The post New interactive World Wide Telescope tour chronicles career of Harvard-Smithsonian astronomer John Huchra appeared first on Smithsonian Insider.

A new species of Brazilian leaf beetle named Cachiporra extremaglobosa, (which translated means the “extremely globular billy club leaf beetle,”) was recently discovered by scientists at the Smithsonian’s National Museum of Natural History.

The post “Billy club” leaf beetle has been hiding in Smithsonian collections since 1959 appeared first on Smithsonian Insider.

NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star.

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On April 4 the Smithsonian and the Massachusetts Institute of Technology will launch VANISHED, an 8-week online/offline environmental disaster mystery game for middle-school children, meant […]

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Evidence for a diversified sea-based economy among North American inhabitants dating from 12,200 to 11,400 years ago is emerging from three sites on California's Channel Islands.

The post New archaeological evidence reveals California’s Channel Islands as North America’s earliest seafaring economy appeared first on Smithsonian Insider.

As researchers investigate the impact of the Burmese python in the Everglades, scientists from the Smithsonian Institution, South Florida Natural Resources Center and the University of Florida examined the snake’s predation of the area’s birds. They found that birds, including endangered species, accounted for 25 percent of the python’s diet in the Everglades.

The post Invasive Burmese pythons are taking a toll on Florida’s native birds appeared first on Smithsonian Insider.

There is a new candidate for coldest known star: a brown dwarf with about the same temperature as a hot cup of coffee. That’s cool enough to begin crossing the blurry line between small cold stars and big hot planets.

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Faced with insufficient time and inadequate library resources to tackle the problem on their own, they instead posted a catalog of specimen images to Facebook and turned to their network of colleagues for help.

The post Facebook friends help scientists quickly identify nearly 5,000 fish specimens collected in Guyana appeared first on Smithsonian Insider.

A team of scientists from the Smithsonian Environmental Research Center in Edgewater, Md., is taking a closer look at how rising acidification of ocean water may be impacting estuaries and near shore environments on the Chesapeake Bay

The post Oysters on floating plates help scientists study acidification and shell growth appeared first on Smithsonian Insider.

If intelligent and more advanced civilizations exist on other planets then its a good bet that some of these civilizations turned to asteroid mining long ago. If so, the hallmarks of their mining activities, such as unusual dirty halos of cast-off dust and debris around large asteroids, might be detectable from earth.

The post Evidence of asteroid mining in our galaxy may lead to the discovery of extraterrestrial civilizations appeared first on Smithsonian Insider.

Giant squid eye, 2008 Giant squid have the largest eyes in the animal kingdom—at up to 10 inches in diameter, they are the size of […]

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In a recent study of the mating behavior of these Asian spiders, researchers found that 87.5 percent of males had both palps amputated during copulation.

The post Don’t pick a fight with a eunuch spider. It has nothing to lose appeared first on Smithsonian Insider.

A team of scientists led by the Smithsonian Institution has discovered a fossilized dinosaur skull and neck vertebrae that not only reveal a new species, but also an evolutionary link between two groups of dinosaurs.

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A remarkable 5,000-year-old deposit of bones representing an entire herd of Persian gazelles recently discovered in northeastern Syria is firm evidence, scientists say, of an ancient hunting practice largely responsible for the near extinction of gazelles in this region today.

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In addition to the species name, Leafsnap provides high-resolution photographs and information about the tree's flowers, fruit, seeds and bark—giving the user a comprehensive understanding of the specie

The post Leafsnap, a new mobile app that identifies plants by leaf shape, is launched by Smithsonian and collaborators appeared first on Smithsonian Insider.

Smithsonian scientists have discovered hundreds of new species around the world. To mark this year’s International Day for Biological Diversity, May 22, here is a […]

The post Slideshow: Species discovered by Smithsonian researchers the past decade appeared first on Smithsonian Insider.

One of the most challenging aspects of this research is simply studying these insects as they are falling, says Yanoviak, a tropical arthropod ecologist at the University of Arkansas, Little Rock. Small body size, rapid descent, and the long distances that they can fall, make accurate data taking a challenge.

The post Lofty experiments with gliding ants reveals secrets of their unusual flight appeared first on Smithsonian Insider.

Researchers from the Smithsonian Institution and the University of Florida have announced the discovery of a bone fragment, approximately 13,000 years old, in Florida with an incised image of a mammoth or mastodon.

The post Bone fragment is only Ice Age artwork from America to show a “proboscidean” appeared first on Smithsonian Insider.

A new genetic study by a team of Cuban and American researchers confirms that American crocodiles are hybridizing with wild populations of critically endangered Cuban crocodiles, which may cause a population decline of this species found only in the Cuban Archipelago.

The post Genetic study confirms American crocodiles and critically endangered Cuban crocodiles are hybridizing in the wild appeared first on Smithsonian Insider.

Using 2-dimensional and 3-dimensional CT scans, Natural History Museum anthropologists found that the brain and major organs were removed and rolls of linen filled out the abdominal cavity. This mummification method is evidence of superior embalming, indicating a person of higher status.

The post Video: A mummy ‘grows’ with CT scans and 3D digital technology appeared first on Smithsonian Insider.

A small-eel like fish newly discovered in a cave in the Republic of Palau in the western Pacific represents an extremely primitive "living fossil."

The post Video: Newly discovered eel a “living fossil” appeared first on Smithsonian Insider.

Two studies appearing in the Aug. 25 issue of the journal Nature provide new insights into a cosmic accident that has been streaming X-rays toward Earth since late March. NASA's Swift satellite first alerted astronomers to intense and unusual high-energy flares from the new source in the constellation Draco.

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What Google is attempting for books, the University of California, Berkeley, plans to do for the world's vertebrate specimens: store them in "the cloud."

The post New “cloud-based” storage initiative to make vertebrate research collections available worldwide appeared first on Smithsonian Insider.

Two scientists at the Smithsonian Institution have been honored with the Presidential Early Career Award for Scientists and Engineers for their innovative research and scientific leadership. It is the highest honor bestowed by the U.S. government on science and engineering professionals in the early stages of their independent research careers.

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