NEWS OF THE WEEK
CARBON CREDITS UNDER FIRE KYOTO PROTOCOL: United Nations examines alleged abuse of carbon-trading system
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credits it awards to firms that claim to be reducing greenhouse gas emissions in China and elsewhere. Critics contend that the firms are gaming the carbon-trading system that awards credits to industrial companies that need to meet Kyoto protocol obligations for carbon emissions. The executive board of the UN’s Clean Development Mechanism (CDM), the body that registers and issues carbon credits under the Kyoto protocol, says it will study six projects whose operators receive credits for destroying the fluorocarbon HFC-23, a potent greenhouse gas. CDM has awarded credits to projects in China, India, South Korea, Mexico, and Argentina, where factories manuARK EMA
Arkema has received carbon credits for its HCFC-22 plant in China.
HE UNITED NATIONS is reviewing carbon
RED WINE MIMICS DEFENDED ACS MEETING NEWS: Sirtris says controversial antiaging compounds act at an allosteric site OH HO
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Resveratrol
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RUG CANDIDATES meant to emulate the antiag-
ing effects of the red wine component resveratrol work by binding to their enzyme target at a site outside the active site, according to research presented on Aug. 22 at the American Chemical Society national meeting in Boston. The discovery adds a new twist to a debate over whether the molecules, from GlaxoSmithKline subsidiary Sirtris Pharmaceuticals, work as claimed. Resveratrol extends life span in fruit flies and worms, and it’s been suggested that the compound works by acting on enzymes, called sirtuins, that remove acetyl groups from proteins. Sirtris was founded with the goal of activating the sirtuin pathway, thought to have a hand in the antiaging benefits of calorie restriction, to treat diseases of aging. The company developed a series of potential drug candidates, such as SRT1720, which it said were more potent sirtuin activators than resveratrol is. In 2008, GSK acquired Sirtris for $720 million. But as early as 2005, scientists were debating whether WWW.CEN-ONLINE.ORG
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facture the refrigerant HCFC-22. The HFC-23 destroyed at the facilities is a by-product that could otherwise be legally released to the atmosphere. Critics claim that chemical firms are producing more HCFC-22 than the market demands to profit from the carbon credits. The projects under review belong to five Chinese and one Indian chemical maker and are aided by investments from financial firms in Europe, one of the places in the developed world where carbon credits are sold. Thirteen similar projects registered by CDM have not been singled out for review. For example, French chemical company Arkema has a Chinese HCFC-22 joint venture for which it has earned carbon credits. And U.K.-based Ineos recently requested carbon credits from CDM for an HCFC-22 project in South Korea. A European environmental group, CDM Watch, has demanded that the UN cut carbon credits it awarded to the projects by more than 90%. The reduction “would remove the current financial incentive that causes plants to produce gas for the sole purpose of getting paid to destroy it,” says CDM Watch Director Eva Filzmoser. The carbon credit marketplace is likely to change when the Kyoto protocol expires in 2012. The EU’s climate commissioner, Connie Hedegaard, called on the UN to put in place more stringent restrictions on credits for industrial projects after 2012. A first step toward a more advanced carbon market would be an overhaul of CDM, she said.—MELODY VOITH
resveratrol was a bona fide activator of SIRT1, the most widely studied human sirtuin enzyme. By 2009, three independent teams concluded that Sirtris’ method for measuring SIRT1 activation was flawed because resveratrol activated SIRT1 only in the presence of a fluorescent peptide substrate used to measure its acetyl-removing activity. In January, researchers at Pfizer further fueled the controversy by reporting that Sirtris’ SIRT1-targeted compounds don’t actually activate SIRT1. At the meeting, Ross L. Stein, vice president of discovery research at Sirtris, fired back at critics. He said Sirtris’ compounds do activate SIRT1. He said his team’s data, recently published in the Journal of Biological Chemistry (DOI: 10.1074/jbc.M110.133892), suggest that the molecules act by binding to an allosteric site on the enzyme. Matt R. Kaeberlein of the University of Washington, who questioned Sirtris’ assay in 2005 but did not attend the presentation, says that although an allosteric mechanism is a good fit for the data in Sirtris’ publication, the antiaging relevance of the company’s compounds will ultimately be determined not by biochemical experiments but by animal models and clinical trials. “I don’t think this study really means much for the field of aging-related science as a whole,” he said. The presentation came just more than a week after GSK asked two employees, both former Sirtris executives, to cease their association with a nonprofit group that sells resveratrol supplements online.—CARMEN DRAHL
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