NEWS OF THE WEEK
HOW INSECT ANTIFREEZE WORKS BIOCHEMISTRY: A protein’s long-range
interactions affect hydrogen bonds
Havenith’s team studied a protein from larvae of the fire-colored beetle Dendroides canadensis.
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AR OWNERS MIGHT have to buy antifreeze
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every winter, but some creatures that survive in frigid climes make their own. Researchers have now obtained new insights into how insect antifreeze—a protein—works. The finding could help the food industry make additives that protect crops from frost or extend the shelf life of frozen foods. Antifreeze proteins derived from fish are already used in some frozen desserts. Antifreeze proteins have a tricky job. They must bind to ice crystals to prevent their growth while engulfed by much larger amounts of liquid water. And they must do so at low concentrations, far lower than those of ethylene glycol antifreeze in a car. Some antifreeze proteins have a particular arrangement of threonine amino acids
EPA FINALIZES BOILER RULE
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AIR POLLUTION: Standards will reduce hazardous emissions from chemical plants, refineries
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FTER YEARS OF DELAY, the Environmental
Protection Agency has finalized tough air pollution standards for large industrial boilers found at oil refineries, chemical plants, and other manufacturing facilities. But the soonest the rules can take effect is 2016. For the first time, the steam-producing systems used to generate heat and power will face strict limits on emissions of mercury, acid gases, and fine particulate matter such as soot. The regulations are expected to reduce mercury emissions by 1.6 tons per year, or about 3% initially, for instance. EPA, however, will give boiler operators three years to meet the standards, with the option to request an additional year. EPA first sought to regulate boiler emissions in 2004. But a federal appeals court in 2007 struck down the agency’s original standard, saying it violated the Clean Air Act. The rule was reissued in 2011 but industry groups blasted that version, arguing its emission limits WWW.CEN-ONLINE.ORG
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that forms an ice-binding site. But because not all antifreeze proteins share this arrangement, researchers have proposed that other interactions must also be involved. Martina Havenith of Ruhr University in Germany and coworkers support that idea by demonstrating that an antifreeze protein affects the organization of water molecules up to 20 Å, or seven layers of water, away from the ice-binding site (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1214911110). This long-range interaction affects hydrogen bonding and likely interferes with ice formation, the authors say. The team examined an antifreeze protein from the fire-colored beetle Dendroides canadensis. They dissolved the protein in water and analyzed the water molecules’ motions with terahertz spectroscopy and computer simulations to see the long-distance action. This is the first time scientists have shown this interaction between an antifreeze protein and water molecules, though it’s not unheard-of for water to affect protein activity, says biochemist Kim A. Sharp of the University of Pennsylvania. He cautions, though, that researchers did not study the protein at the freezing temperatures at which it’s active. But it’s still possible, he says, that long-range water ordering lets antifreeze proteins reach farther and prevent freezing more efficiently than they could with a threonine ice-binding site alone.—CARMEN DRAHL
were unachievable. EPA agreed to revise the measure after gathering additional data from industry. “We appreciate EPA’s thoughtful consideration of these rules and willingness to make sensible changes,” says the American Chemistry Council, a chemical industry trade group. “While we need to review the rules for technical details, it appears that a number of improvements have been made.” The changes will require pollution controls at about 2,300 of the largest and highest-emitting boilers nationwide. Another 197,000 smaller boilers will be able to meet the rule by conducting periodic maintenance or routine tune-ups, EPA says. Although the most restrictive emission limits will affect less than 1% of the nation’s nearly 1.5 million boilers, they will impose major costs on the U.S. manufacturing sector. Industry will have to spend between $1.3 billion and $1.5 billion annually to meet the standards, according to EPA estimates. However, the agency says the emission reductions brought about by the new rule will thwart up to 8,100 premature deaths, prevent 5,100 heart attacks, and avert 52,000 asthma attacks each year. The new standards will encourage U.S. industry to use cleaner-burning fuels and to make improvements in energy efficiency, says James Bradbury, senior associate at the World Resources Institute, a think tank. “This is good news for the manufacturing workforce, for public health, and for the climate,” he remarks.—GLENN HESS
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