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转载:异养型二氧化碳的固定----Heterotrophic Carbon Dioxide Fixation

已有 4462 次阅读 2008-11-2 20:58 |个人分类:微生物生理学专栏|文章来源:转载

Harland G. Wood (1907-1991)

 

异养型二氧化碳固定的发现者:Harland G. Wood

 

J. Biol. Chem., Vol. 280, Issue 18, 15, May 6, 2005

 

The Discovery of Heterotrophic Carbon Dioxide Fixation by Harland G. Wood

 

Nicole Kresge, Robert D. Simoni, and Robert L. Hill

 

 

Heavy Carbon as a Tracer in Heterotrophic Carbon Dioxide Assimilation (Wood, H. G., Werkman, C. H., Hemingway, A., and Nier, A. O. (1941) J. Biol. Chem. 139, 365-376)

 

The Mechanism of Carbon Dioxide Fixation by Cell-free Extracts of Pigeon Liver: Distribution of Labeled Carbon Dioxide in the Products (Wood, H. G., Vennesland, B., and Evans, E. A. (1945) J. Biol. Chem. 159, 153-158)

 

The Fixation of Carbon Dioxide in Oxalacetate by Pigeon Liver (Utter, M. F., and Wood H. G. (1946) J. Biol. Chem. 164, 455-476)

 

Harland Goff Wood (1907-1991) was born in Delavan, a small village in south central Minnesota. He attended Macalester College in Minnesota where he majored in chemistry. Wood graduated during the Depression, and because jobs were scarce, he decided that he would need a higher degree to meet the competition. His biology professor, O. T. Walters, suggested he apply for a fellowship in bacteriology at Iowa State College. Wood's application was reviewed by Chester Werkman, author of a previous Journal of Biological Chemistry (JBC) Classic (1), who was starting to investigate the chemistry of bacterial fermentations and was looking for a chemistry student. Werkman accepted Wood's application, and in 1931 Wood moved to Ames, Iowa.

 

For his thesis research, Wood was assigned an investigation of fermentation by propionic acid bacteria, a group of bacteria that ferment compounds such as glycerol with the formation of propionic acid. He started by looking into glucose fermentation and determined that succinate is formed from glucose. Next, he decided to investigate glycerol fermentation in propionic acid bacteria. He determined the products of glycerol fermentation in a bicarbonate buffer system and calculated the carbon and oxidation-reduction balances to account for the carbon of the fermented substrate. Surprisingly, Wood found that the products from glycerol fermentation contained more carbon than was supplied by the fermented glycerol. He subsequently discovered that the extra carbon was derived from CO2 in the buffer and eventually proposed that CO2 and pyruvate combine to form oxalacetate, which is subsequently reduced to succinate (2, 3). This ultimately became known as the Wood-Werkman reaction.

 

However, as with many new findings, Wood's discovery of heterotrophic CO2 fixation was extremely controversial. At that time CO2 fixation was believed to occur only in plants and a few unusual autotrophic bacteria, and the publication of his results was met with much skepticism. For example, C. B. van Niel stated that, "Wood and Werkman claim that carbon dioxide is reduced during the fermentation of glycerol by propionic acid bacteria. The published results cannot, however, be considered conclusive, although the data do seem to favor their claim" (4). Even Wood thought his results might be wrong and didn't include them in his thesis.

 

In 1935 Wood went to the University of Wisconsin where he worked as a postdoctoral fellow with W. H. Petersen for 4 years. At Wisconsin he studied the growth factor requirements for propionic acid bacteria with Ed Tatum. They showed, for the first time, that vitamin B1 is required for the growth of a microorganism (5).

 

Werkman then offered Wood a position as an Assistant Research Professor at Iowa State, and he returned to Ames in 1936 to continue his work on CO2 fixation. At that time they only had indirect evidence that CO2 was fixed in succinate. Wood's brother, who was studying for his Ph.D. and M.D. at the University of Minnesota, mentioned some studies being done with 13C and suggested that he collaborate with a young physicist named Alfred Nier who would be able to supply labeled carbon and measure it with a mass spectrometer. As reported in the JBC Classic reprinted here, Wood was able to prove that 13CO2 is fixed in succinate and that the 13C is located exclusively in the carboxyl groups (6). Thus, Wood concluded, "all the carbon dioxide is fixed originally by union of 3-carbon and 1-carbon compounds." Eventually, as shown in a previous JBC Classic (1), Werkman and Merton Utter would also prove that a C1 + C2 reaction is possible.

 

Although the labeling experiments lent credibility to heterotrophic CO2 fixation, Wood was convinced that the full significance of CO2 utilization would not be fully appreciated until it was demonstrated in animals. Unfortunately, Earl Evans and Louis Slotin beat Wood to it and, using 11C, demonstrated CO2 fixation by the liver in 1940 (7).

 

Up until this time, all of Wood's 13C experiments had been done in collaboration with Nier. However, it became increasingly clear that having a 13C facility at Iowa State would facilitate the studies. Wood and several other microbiologists in the department built a mass spectrometer and a thermal diffusion column to concentrate 13C. The thermal diffusion column extended five stories in an elevator shaft from the basement to the attic of the science building. Shortly after helping to build this new research facility, Wood accepted an Associate Professorship in the Department of Physiological Chemistry at the University of Minnesota. In 1943 he moved to Minnesota and started studying the conversion of [13C]NaHCO3 to glycogen in animals. These studies are the subject of the second and third JBC Classics reprinted here.

 

In the second Classic, Wood demonstrates CO2 fixation in pigeon liver extracts by showing that 13CO2 can combine with pyruvate and fumarate to produce products with 13C-labeled carboxyl groups. However, his attempts to investigate the mechanism of fixation were unsuccessful. Using the liver extracts, he was unable to demonstrate the formation of oxalacetate from pyruvate and CO2. However, Wood would eventually discover that the reaction does occur in pigeon liver extracts when ATP is added to the reaction mixture. These results are reported in the final JBC Classic, along with the finding that ATP also stimulates CO2 fixation when fumarate and pyruvate are used as substrates.

 

In 1946 Wood accepted a position as Chairman of the Department of Biochemistry at the School of Medicine at what was then Western Reserve University in Cleveland (the University merged with Case Institute of Technology in 1968 to become Case Western Reserve University). As Chairman, Wood made many changes. He brought in an entire new faculty to focus on using isotopic tracers to study metabolism, and he reformed the curriculum at the medical school. He also instituted a policy that all faculty honoraria should go onto a student travel fund because he believed that outside activities should have an intrinsic value based on science and not money.

 

Wood retired as chairman in 1965 so that he could have more time for research, which for him meant spending time at both the bench and his desk. In the 19 years between his 70th birthday and his death in 1991 he published 96 papers. The overall direction of Wood's research continued to follow the trail of CO2. His later scientific contributions include establishing the reaction mechanism of transcarboxylase from propionic acid bacteria, discovering a novel pathway for CO fixation in a group of anaerobic bacteria, and studying the role of pyrophosphate and polyphosphate as energy sources.

 

Wood was president of the American Society of Biological Chemistry from 1959 to 1960 and president of the International Union of Biochemistry from 1982 to 1983. He was also a member of the JBC Editorial Board and was instrumental in eliminating self-perpetuating appointments when he resigned after his 5-year appointment was up, saying "Listen, if all you guys died tomorrow, a good board could be picked the next day to replace you" (8). Wood was a member of the National Academy of Sciences and the American Academy of Arts and Sciences and served on the President's Science Advisory Committee under Presidents Johnson and Nixon. 1

全文见:

http://www.jbc.org/cgi/content/full/280/18/e15



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