Peter D. Mitchell

Peter Dennis Mitchell (September 29 1920–April 10 1992) [cite web
url=http://www-biology.ucsd.edu/~msaier/transport/petermitchell/MitchellFrame-1.html
title=Peter Mitchell and the Vital Force
author=Milton H. Saier Jr
accessdate=2007-03-23] was a British biochemist who was awarded the 1978 Nobel Prize for Chemistry for his discovery of the chemiosmotic mechanism of ATP synthesis.

Mitchell was born in Mitcham, Surrey, England [cite web
url=http://www.nndb.com/people/607/000100307/
title=Peter Mitchell Bio at NNDB
accessdate=2007-03-23
author=NNDB] .

Biography

Peter D. Mitchell was born in Mitcham, Surrey on 29 September 1920. His parents were Christopher Gibbs Mitchell, a civil servant, and Kate Beatrice Dorothy (née) Taplin. He was educated at Queen's College, Taunton, and at Jesus College, Cambridge where he studied the Natural Sciences Tripos specialising in biochemistry.

He accepted a research post in the Department of Biochemistry, Cambridge, in 1942, and received the degree of Ph.D. in early 1951 for work on the mode of action of penicillin. In 1955 he was invited by Professor Michael Swann to set up a biochemical research unit, called the Chemical Biology Unit, in the Department of Zoology, Edinburgh University, where he was appointed to a Senior Lectureship in 1961, to a Readership in 1962, although ill health led to his resignation in 1963.

Independent researcher

From then to 1965, he supervised the restoration of a Regency-fronted Mansion, known as Glynn House, near Bodmin, Cornwall - adapting a major part of it for use as a research laboratory. He and his former research colleague, Jennifer Moyle founded a charitable company, known as Glynn Research Ltd., to promote fundamental biological research at Glynn House and they embarked on a programme of research on chemiosmotic reactions and reaction systems [cite journal
last=Mitchell
first=Peter
title=Chemiosmotic coupling in oxidative and photosynthetic phosphorylation
journal=Biol. Rev. Cambridge Phil Soc.
volume=41
pages=445–502
year=1966
month=Aug
pmid=5329743
url=http://www.garfield.library.upenn.edu/classics1978/A1978ET22100003.pdf
doi=10.1111/j.1469-185X.1966.tb01501.x] [cite journal
last=Mitchell
first=Peter
journal=J Bioenerg
year=1972
month=May
volume=3
issue=1
pages=5–24
title=Chemiosmotic coupling in energy transduction: a logical development of biochemical knowledge
pmid=4263930
doi=10.1007/BF01515993] [cite journal
last=Greville
first=G.D.
year=1969
title=A scrutiny of Mitchell's chemiosmotic hypothesis of respiratory chain and photosynthetic phosphorylation
journal=Curr. Topics Bioenergetics
volume=3
pages=1–78.] [cite journal
journal=Biochem J.
year=1970
month=Feb
volume=116
issue=4
pages=5–6
title=Aspects of the chemiosmotic hypothesis
last=Mitchell
first=Peter
pmid=4244889
url=http://www.pubmedcentral.gov/picrender.fcgi?artid=1185429&blobtype=pdf] [cite journal
journal=J Theor Biol
year=1976
month=Oct
volume=62
issue=2
pages=327–67
title=Possible molecular mechanisms of the protonmotive function of cytochrome systems
last=Mitchell
first=Peter
pmid=186667
doi=10.1016/0022-5193(76)90124-7] .

In 1978 he won the Nobel Prize in Chemistry "for his contribution to the understanding of biological energy transfer through the formulation of the chemiosmotic theory." [cite web
title=Mitchell's 1978 Nobel speech
url=http://nobelprize.org/chemistry/laureates/1978/mitchell-lecture.html
accessdate=2007-03-23]

Chemiosmotic hypothesis

In the 1960s, ATP was known to be the energy currency of life, but the mechanism by which ATP was created in the mitochondria was assumed to be by substrate-level phosphorylation. Mitchell's chemiosmotic hypothesis was the basis for understanding the actual process of oxidative phosphorylation. At the time, the biochemical mechanism of ATP synthesis by oxidative phosphorylation was unknown.

Mitchell realised that the movement of ions across an electrochemical membrane potential could provide the energy needed to produce ATP. His hypothesis was derived from information that was well known in the 1960s. He knew that living cells had a membrane potential; interior negative to the environment. The movement of charged ions across a membrane is thus affected by the electrical forces (the attraction of plus to minus charges). Their movement is also affected by thermodynamic forces, the tendency of substances to diffuse from regions of higher concentration. He went on to prove that ATP synthesis was coupled to this electrochemical gradient [cite journal
last=Mitchell
first=Peter
title=Coupling of phosphorylation to electron and hydrogen transfer by a chemi-osmotic type of mechanism
journal=Nature
volume=191
month=Jul
year=1961
pages=144–8
pmid=13771349
url=http://www.garfield.library.upenn.edu/classics1986/A1986E685800002.pdf
doi=10.1038/191144a0] .

His theory was confirmed by the discovery of ATP synthase, a membrane-bound protein that uses the potential energy of the electrochemical gradient to make ATP.

References

ee also

*Bioenergetics

External links

* [http://www.life.uiuc.edu/crofts/bioph354/mitchell.html Peter D. Mitchell biography]