Peter D. Mitchell (September 29 1920- April 10 1992) was a British biochemist who was awarded the 1978 Nobel Prize for Chemistry for his discovery of the chemiosmotic mechanism of ATP synthesis.

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, oxidative phosphorylation was unknown as a biochemical mechanism to make ATP.

Mitchell realised that the movement of ions across a membrane had an electrochemical potential to do work that could be utilised to produce ATP. His hypothesis was derived from information that was well known in the 1960's. 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 was created by this electrochemical gradient.

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.

Mitchell's chemiosmotic theory turned out to be one of the two seminal discoveries in biology in the 20th century (DNA being the other).

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, and where he remained ill health led to his resignation in 1963.

Independant 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.

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."

References

---

1. Saier, Milton. Peter Mitchell Biography
2. Mitchell, Peter. Coupling of phosphorylation to electron and hydrogen transfer by a chemi-osmotic type of mechanism. Nature 191, 144 - 148 (08 July 1961). Download classics text PDF.
3. Mitchell, P. (1966) Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation, Glynn Research, Bodmin. Download classics text PDF.
4. Mitchell, P. (1968) Chemiosmotic Coupling and Energy Transduction, Glynn Research, Bodmin.
5. Greville G.D. (1969) A scrutiny of Mitchell's chemiosmotic hypothesis of respiratory chain and photosynthetic phosphorylation. Curr. Topics Bioenergetics 3, 1–78.
6. "Aspects of the chemiosmotic hypothesis" by Peter Mitchell in The Biochemical Journal (1970) Volume 116, pages 5P-6P. Download full text PDF.
7. Mitchell, P. Possible molecular mechanisms of the protonmotive function of cytochrome systems. J Theor Biol. 1976 Oct 21;62(2):327-67. doi:10.1016/0022-5193(76)90124-7
8. Mitchell's 1978 Nobel speech.

1920 births | 1992 deaths | English biochemists | British biochemists | Nobel Prize in Chemistry winners

Peter Dennis Mitchell | Peter Dennis Mitchell | Peter D. Mitchell | Митчелл, Питер Деннис