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CHEMISTRY NOBEL Researchers from three countries share prize for ATP synthase discoveries
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hree researchers received word last week from the Royal Swedish Academy of Sciences that they had won the world's most prestigious chemical honor— the 1997 Nobel Prize in Chemistry. One-half of this year's $1 million prize is being shared by emeritus professor of biochemistry Paul D. Boyer of the University of California, Los Angeles, and senior scientist John E. Walker of the Medical Research Council Laboratory of Molecular Biology, Cambridge, England. They are being honored for having elucidated the enzymatic mechanism by which ATP synthase (ATPase) catalyzes the synthesis of adenosine triphosphate (ATP), the energy currency of living cells. The other half of the prize goes to emeritus professor of biophysics Jens C. Skou of Aarhus University, Denmark, for his discovery of the first molecular pump, an ion-transporting enzyme called Na+-K+ ATPase. "It's a sensational award to three very deserving nominees," comments biochemistry professor Robert H. Fillingame of the University of Wisconsin Medical School, Madison. "This is a very rewarding day for the ATPase community in general," adds biochemistry professor William S. Allison of the Univer-
sity of California, San Diego. Fillingame and Allison both specialize in the molecular mechanism of ATP synthesis. In the late 1970s, Boyer proposed the "binding-change hypothesis," a detailed molecular mechanism for the ATPase-catalyzed synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate in animal mitochondria, plant chloroplasts, and bacterial cell membranes. Walker verified the mechanism by obtaining the amino acid sequence of ATPase in the early 1980s and the first highresolution crystal structure of the enzyme's catalytic domain in 1994. "Walker's work complements Boyer's in a remarkable manner," says the academy. Boyer hypothesized that ATPase's three catalytic sites pass through "loose," "tight," and "open" conformational states in each of three catalytic cycles. In the first cycle, ATP synthesis in-
volves binding of ADP and phosphate to an active site in the loose state, energydriven conformational conversion of the site to the tight state, and subsequent synthesis of ATP. ATP is actually released in the enzyme's second catalytic cycle, when the site converts from loose to open. In the enzyme's third catalytic cycle, the site reverts from open to loose, making it capable of binding substrate once again. Walker's crystal structure showed that at any one moment the conformations of each of ATPase's three catalytic sites were different, a finding consistent with Boyer's model. The structure also suggested a way that energy could be coupled to ATP synthesis by relative rotation of the enzyme's domains. This has been borne out by subsequent research, including a recent study by a Japanese group in which an ingenious technique was used to visualize the rotation process. "It's an experience of a lifetime," Boyer says of winning the Nobel Prize. "The support of basic research by our society makes this kind of work possible." Walker, reached in England, told C&EN: "People had hinted to me that I should listen to the news today [Oct. 15], so I'd gone home to listen to the ra-
(From left) Walker, Boyer, and Skou shared Nobel Prize in Chemistry. AP photo/Findlay Kember
AP photo/Lacy Atkins
AP photo
Binding-change mechanism of ATP synthesis
Boyer's mechanism predicted that ATPase's catalytic sites (colored segments) have different conformational states at any one time—loose (L), tight (T), and open (O). The complete catalytic process includes three sequential catalytic cycles, only one of which is shown here. ADP = adenosine diphosphate, ATP = adenosine triphosphate, P£ = inorganic phosphate. OCTOBER 20, 1997 C&EN 11
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dio. I heard about the physics prize, but there was no mention of chemistry, so I assumed I could forget about that. I was consoling myself by wandering about my garden" when a German radio station phoned, "offering congratulations. . . . Then I came back to the lab and found the fax from the Swedish academy." With his prize winnings, Walker said, "I was thinking I'd buy myself a new bicycle"—a gift in keeping with the theme of rotatory catalysis. Skou was honored for his discovery, in the late 1950s, of Na+-K+ ATPase, the first enzyme found to promote directed
transport through cell membranes. This specialized ATPase maintains the proper balance of sodium and potassium ions across membranes, consuming about one-third of all the ATP produced in the body in the process. The energy stored in the ion gradients is used to drive essential cell functions, such as nerve impulse transmission. Numerous enzymes have since been demonstrated to have related similar functions—including Ca2+ ATPase, which helps control muscle contraction, and H+-K+ ATPase, which plays a key role in digestion. Stu Borman
Work on cool atoms traps Nobel Prize in Physics The 1997 Nobel Prize in Physics has been awarded to physics professors Steven Chu of Stanford University and Claude Cohen-Tannoudji of College de France and Ecole Normale Superieure, Paris, and physicist William D. Phillips at the National Institute of Standards & Technology, Gaithersburg, Md. They are being recognized for development of methods to cool and trap neutral atoms with laser light Chu, Cohen-Tannoudji, and Phillips have developed methods that allow gases to be cooled to temperatures approaching absolute zero (-273 °C) without condensing. At such temperatures, gases normally will freeze. But when bombarded with laser light, the gas atoms slow down without freezing. The slow-moving atoms then can be trapped in magnetic fields and studied in detail
China captures more petrochemical investments The lure of double-digit growth continues to draw U.S. chemical companies to China. Last week, petrochemical giants Exxon and Phillips Petroleum each announced plans for new chemical complexes expected to begin supplying the huge Chinese market by early next century. Exxon China, an affiliate of Exxon, will be joined by Saudi Arabia's Aramco in a feasibility study with Fujian Petrochemical Co. (FPC) to build a refinery and petrochemical complex in Fujian Province of central China. The project involves the expansion of an existing FPC refinery and the addition of a 1.3 billionlb-per-year ethylene cracker, a 1 billionlb-per-year polyethylene facility, and a 12 OCTOBER 20, 1997 C&EN
By allowing the study of atomic properties with greater accuracy than has been possible before, the methods "have contributed greatly to increasing our knowledge of the interplay between radiation and matter" and "have opened the way to a deeper understanding of the quantumphysical behavior of gases at low temperature," says the Royal Swedish Academy of Sciences, which decided the award "Applications [are] just around the corner," adds the academy. Already, the techniques have led to thefirstobservation of Bose-Einstein condensate, a new state of matter in which many atoms assume a common quantum state. Other possible applications include design of ultraprecise atomic clocks and development of atomic lasers for production of very small electronic components. Maureen Rouhi 660 million-lb-per-year polypropylene facility for completion in 2003. When the project was first announced in August, Exxon was to be an equal partner with FPC (C&EN, Aug. 11, page 15), but the Exxon portion will now be shared with Aramco, which will provide the crude oil feedstock for the facility. At a Beijing signing ceremony on Oct. 10, Phillips and local manufacturers announced their plans for three petrochemical ventures, to be built following feasibility studies. The first is a $2.4 billion chemical complex, split equally with Lanzhou Chemical Industry Corp. (LCIC), that would include a 1.3 billion-lb-per-year ethylene cracker and annual polymer capacity of 1.2 billion lb of polyethylene and 660 million lb of polypropylene. The proposed complex would be located at an existing LCIC facility in central China and would start up in 2004 or 2005. Phillips also has plans for a new
100 million-lb-per-year styrene-butadiene copolymer facility and an expansion of a joint polyethylene facility with Shanghai Petrochemical in Jinshanwei on China's central coast, near Shanghai. The polyethylene expansion will triple capacity to 750 million lb per year at a facility currently under construction. Completion of the copolymer plant and the expansion are set for 2002. W. Wayne Allen, chairman and chief executive officer at Phillips, notes that these projects "demonstrate our commitment to China and its efforts to build a world-class petrochemical industry." The influx of foreign money is important to the development of the petrochemical industry in China, according to Dave Durand of Phillip Townsend Associates, Houston. Many of the existing production units are small and isolated; large, well-integrated complexes are needed to meet the growing local demand. Durand predicts annual growth rates of 11 to 12% for polyethylene and 13% for polypropylene in China for the next five years. China continues to rely heavily on imports of polyolefin products. In 1996, 58% of polyethylene demand and 45% of polypropylene demand were met with imported products. With China's polyethylene market second in size only to the U.S., Exxon and Phillips are eager to take advantage of the large opportunity there with shared local production. Paige Morse
Crystal structure offers clues to nitric oxide regulation Researchers are getting their first look at the catalytic portion of the enzyme that makes the signaling molecule nitric oxide (NO). An X-ray crystal structure of that key part of one form of nitric oxide synthase likely will yield clues to how the body makes and regulates the production of the reactive free radical. Short-lived NO serves as a messenger in processes as diverse as neural signaling, blood pressure control, and immune regulation. It's also used defensively by the immune system to fight infection. Too much or too little NO has been implicated in many serious conditions including septic shock, hypertension, impotence, and susceptibility to infection. "Here's a molecule that can walk
