Peter D. Mitchell
|Peter Dennis Mitchell|
|Born||29 September 1920
Mitcham, Surrey, England
|Died||10 April 1992
Bodmin, Cornwall, England
|Alma mater||Jesus College, Cambridge, University of Edinburgh|
|Known for||discovery of the mechanism of ATP synthesis|
|Notable awards||Nobel Prize in Chemistry (1978)
Copley Medal (1981)
Peter Dennis Mitchell, FRS (29 September 1920 – 10 April 1992) was a British biochemist who was awarded the 1978 Nobel Prize for Chemistry for his discovery of the chemiosmotic mechanism of ATP synthesis.
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. His Uncle was Sir Godfrey Way Mitchell, chairman of George Wimpey. 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.
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. 
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 potential difference 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 positive to negative charges). Their movement is also affected by thermodynamic forces, the tendency of substances to diffuse from regions of higher concentration. He went on to show that ATP synthesis was coupled to this electrochemical gradient.
His hypothesis was confirmed by the discovery of ATP synthase, a membrane-bound protein that uses the potential energy of the electrochemical gradient to make ATP.
- Slater, E. C. (1994). "Peter Dennis Mitchell. 29 September 1920-10 April 1992". Biographical Memoirs of Fellows of the Royal Society 40: 282–226. doi:10.1098/rsbm.1994.0040.
- Milton H. Saier Jr. "Peter Mitchell and the Vital Force". Retrieved 2007-03-23.
- "The Oxford Dictionary of National Biography". 2004. doi:10.1093/ref:odnb/51236.
- NNDB. "Peter Mitchell Bio at NNDB". Retrieved 2007-03-23.
- Mitchell, P. (1966). "Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation". Biological Reviews 41 (3): 445–502. doi:10.1111/j.1469-185X.1966.tb01501.x. PMID 5329743.
- Mitchell, P. (1972). "Chemiosmotic coupling in energy transduction: A logical development of biochemical knowledge". Journal of Bioenergetics 3 (1): 5–24. doi:10.1007/BF01515993. PMID 4263930.
- Greville, G.D. (1969). "A scrutiny of Mitchell's chemiosmotic hypothesis of respiratory chain and photosynthetic phosphorylation". Curr. Topics Bioenergetics 3: 1–78.
- Mitchell, P. (1970). "Aspects of the chemiosmotic hypothesis". The Biochemical journal 116 (4): 5P–6P. PMC 1185429. PMID 4244889.
- Mitchell, P. (1976). "Possible molecular mechanisms of the protonmotive function of cytochrome systems". Journal of Theoretical Biology 62 (2): 327–367. doi:10.1016/0022-5193(76)90124-7. PMID 186667.
- "Mitchell's 1978 Nobel speech". Retrieved 2007-03-23.
- Mitchell, P. (1961). "Coupling of Phosphorylation to Electron and Hydrogen Transfer by a Chemi-Osmotic type of Mechanism". Nature 191 (4784): 144–148. Bibcode:1961Natur.191..144M. doi:10.1038/191144a0. PMID 13771349.