Robert Hill (naturalist)

Robert Hill (born  April 2, 1899 in Leamington Spa , Warwickshire , †  March 15, 1991 ) was a British biochemist .

Hill studied chemistry from 1919 to 1922 at Cambridge University , England. He was accepted by the university after graduating. He worked in the Department of Biochemistry at Cambridge University. In 1932 he began his work on photosynthesis . From 1943 to 1966 he was a member of the "Agricultural Research Council". In 1971 he was elected to the American Academy of Arts and Sciences and in 1975 to the National Academy of Sciences .

Life's work

In 1939 Robert Hill determined that isolated chloroplasts in the presence of reducing compounds (e.g. iron oxalate , potassium hexacyanoferrate (III) (ferricyanide), benzoquinone ) release oxygen under the influence of light . The reaction went down in the literature as the Hill reaction .

The reaction formula of his theory is:

2 H ₂ O + 2 A → light, chloroplasts → 2 AH ₂ + O ₂

A stands for an electron acceptor z. B. Iron (III) compounds. The reaction equation would then be as follows:

2 H ₂ O + 4 Fe ³⁺ → light, chloroplasts → 4 Fe ²⁺ + O ₂ + 4 H ⁺

This process is connected with a previous photolysis of the water.

2 H ₂ O → light, chloroplasts → 4 H ⁺ + O ₂ + 4 e ^-

By this Hill's finding it was conclusively proven that:

• Oxygen is produced without a simultaneous reduction in carbon dioxide
• Oxygen is formed from water and not from carbon dioxide
• the photosynthesis enzymes are located in the chloroplasts
• the light reaction takes place in the transfer of an electron to an electron acceptor against a chemical energy gradient

The statement that the oxygen released results from the splitting of the water was later confirmed by M. Randall, Samuel Ruben, Martin Kamen and JL Hyde. They used heavy oxygen (H ₂ O ¹⁸ ) water that was cleaved by a suspension of Chlorella cells. This heavy oxygen could be detected. Efraim Racker (Cornell University, Ithaca, NY) found that light energy can be replaced by adding high-energy compounds.

swell

1. ^ R. Hill: Oxygen evolution by isolated chloroplasts. In: Nature. Volume 139, 1937, pp. 881-882.
2. ^ R. Hill: Oxygen produced by isolated chloroplasts. In: Proc. R. Soc. London Ser. B. Vol. 127, 1939, pp. 192-210.

literature

• DA Walker: And whose bright presence - an appreciation of Robert Hill and his reaction. In: Photosynth Res. Volume 73, No. 1-3, 2002, pp. 51-54. PMID 16245102 PDF