NEWS OF TH E WEEK
FEDS END PROBE OF TESORO BLAST
The four-year investigation included interviewing past and present employees, reviewing thousands of documents, and consulting with industry experts. Tesoro spokeswoman Tina Barbee tells C&EN that the petroleum refiner “appreciates the government’s diligent and thorough investigation of this incident. We are pleased with this decision, which we believe is consistent with the facts.” The tragedy at the Anacortes refinery “serves as a constant reminder of the importance of our ongoing dedication to continuous improvement in process and personal safety,” Barbee adds. The blast was the deadliest refinery accident in the U.S. since a 2005 explosion killed 15 people and injured 180 at a BP refinery in Texas City, Texas. The federal Chemical Safety & Hazard Investigation Board (CSB) released its final report on the Anacortes accident in May. It said safer practices and better steel could have prevented the deadly explosion at the facility, located about 70 miles north of Seattle on Puget Sound. But CSB also blamed lax oversight by federal and state regulators for the catastrophic rupture of a nearly 40-year-old heat exchanger at the refinery, which leaked and ignited highly flammable hydrogen and naphtha. Equipment at the facility had not been inspected in decades for the type of corrosion that caused the explosion during a maintenance operation, according to the safety board’s investigation.—GLENN HESS
INQUIRY: No charges filed as Justice
Department closes criminal investigation of fatal accident
O ONE WILL FACE criminal charges in connec-
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tion with the April 2010 refinery explosion and fireball that engulfed and killed seven Tesoro workers in Anacortes, Wash., the U.S. Justice Department says. Shortly after the accident, prosecutors and criminal investigators launched an inquiry to determine whether federal environmental and worker safety statutes and regulations were violated. “This tragedy demanded careful and thorough investigation,” says U.S. Attorney Jenny A. Durkan. “I am satisfied that the investigators and the experienced environmental attorneys in my office evaluated all the evidence and determined it does not reach the exacting bar for criminal prosecution.” CSB
A heat exchanger at the Tesoro refinery had not been inspected in decades.
LINKER HELPS DETECT PROTEIN PARTNERS
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Se Bait protein Prey protein Photocross-linking
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Oxidative cleavage
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BIOCHEMISTRY: Cleavable photo-cross-linker aids proteinprotein interaction analysis ROTEIN-PROTEIN INTERACTIONS play impor-
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tant roles in normal body processes and in disease. Scientists often lock interacting proteins together with cross-linkers to better understand these interactions—information that can help lead to drugs that block or promote the protein-protein interplay. Now, a research team in China has developed a cleavable photocross-linking agent that can be genetically engineered into proteins to help study the interactions in living cells. Cross-linking ensures that protein partners stay together for analysis, especially when interactions are weak or transient. But cross-linking techniques generally do not separate or label protein partners before analysis.
INTERACTION LINK In this technique, a Add tags or labels
Mass spectrometry analysis
selenium-based linker is engineered into a bait protein. Photoactivating the linker locks bait and prey proteins together. Oxidatively cleaving it releases the bait, allowing scientists to tag the prey protein for analysis. CEN.ACS.ORG
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ADAPTED FROM J. AM. C HEM. SOC.
Cleavable selenium-based amino acid group
The lack of separation or labeling complicates protein identification and can cause the techniques to detect invalid interactions and fail to recognize valid ones. Peng R. Chen of Peking University and coworkers devised a technique that separates cross-linked interacting proteins prior to analysis and adds a chemical handle that aids detection (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja504371w). The technique begins with a known “bait protein,” which can interact with “prey proteins.” Chen and coworkers engineer a selenium-based amino acid into the bait protein. Photoactivating the amino acid links bait and prey. And oxidatively cleaving it later separates the partners and leaves the selenium group on the prey. The selenium group, now oxidized to a selenenic acid, can then be tagged or labeled to facilitate identification of the prey. The researchers used the technique to profile proteins that bind with a bacterial chaperone protein under acidic “stress” conditions. “Difficulties in isolating cross-linked proteins have been a big impediment to realizing the full power of the photo-cross-linking-MS approach,” comments protein-protein interactions specialist Jennifer Kohler of the University of Texas Southwestern Medical Center, Dallas. “This paper offers an innovative approach to solving this key methodological gap. If selenium cleavage and labeling prove to be robust and reliable in biological lysates, this will be a significant enabling step for cell-based photo-cross-linking.”—STU BORMAN
AUGUST 25, 2014
