- Person
- Melvin Calvin
- Lived
- 1911–1997
- Field
- Biochemistry
- From
- American
The story
Everyone knew in outline what photosynthesis does: plants use sunlight to turn carbon dioxide and water into sugar and release oxygen. But until the 1950s no one knew the chemical steps by which carbon from the air becomes part of a living plant. Melvin Calvin, the son of Jewish immigrants from the Russian Empire, born in St. Paul, Minnesota, in 1911, set out to find them at the University of California’s Radiation Laboratory in Berkeley.
His key tool was carbon-14, a long-lived radioactive form of carbon discovered at Berkeley in 1940. It behaves like ordinary carbon but can be detected, so it can be used to follow carbon atoms through a living system. From 1946 Calvin led a team that included Andrew Benson and James Bassham. They fed single-celled green algae carbon dioxide containing carbon-14 for very short, carefully timed periods, killed the cells instantly and separated the labelled compounds on sheets of paper using chromatography. They could resolve products formed in about five seconds. The first stable product was a three-carbon compound, phosphoglyceric acid. Experiments moving algae from light to darkness showed that the capture of carbon dioxide does not itself need light.
Step by step the team identified the sugars involved and found that a five-carbon sugar, ribulose bisphosphate, is the molecule that captures carbon dioxide. By 1958 they had the whole cycle, in which carbon dioxide is attached to that sugar, turned into larger sugars and the starting molecule regenerated. It is now called the Calvin cycle or, recognising his colleagues, the Calvin–Benson–Bassham cycle. Calvin received the 1961 Nobel Prize in Chemistry for this research; Benson’s share of the credit has since been widely acknowledged.
The cycle is the main route by which carbon enters the living world, so nearly all the food people eat depends on it. Knowing its steps underpins modern plant science, including efforts to raise crop yields and make photosynthesis more efficient, and helps scientists understand how forests, crops and plankton take up carbon dioxide. The tracer technique the team refined also became a standard tool across biology and medicine.
Why it matters
The Calvin cycle is the chemistry behind almost all of the world’s food, and knowing it guides crop and climate research.
About Melvin Calvin
Berkeley chemist, son of Jewish immigrants, who with his team traced how plants turn carbon dioxide into sugar, the Calvin cycle at the root of almost all food on earth. Nobel Prize 1961.
Sources
- Melvin Calvin, Biographical Memoirs Volume 75 National Academy of Sciences
- Melvin Calvin obituary Berkeley Lab Research News
- Melvin Calvin, Biographical NobelPrize.org
- Melvin Calvin Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.