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Melvin CalvinAmerican biochemist
Date of Birth: 08.04.1911
Country:  USA |
Content:
- Early Life and Education
- Career and Scientific Research
- The Calvin Cycle
- Interdisciplinary Research and Later Career
- Awards, Honors, and Legacy
Early Life and Education
Melvin Calvin (known as "Calvin") was born on April 8, 1911, in St. Paul, Minnesota, to Russian-born parents Rosa E. (Hervitz) Calvin and Elias Calvin. From an early age, Calvin displayed an insatiable curiosity and love of learning. By the eleventh grade, he had already decided to pursue chemistry as his career path.
The Calvin family later relocated to Detroit, Michigan, where Calvin attended Denby High School. Despite concerns from his physics teacher that he would "never amount to anything as a scientist," Calvin excelled in his studies. He earned a scholarship to Michigan College of Mining and Technology, where he graduated with a Bachelor of Science degree in 1931.
In 1935, the University of Minnesota awarded Calvin a PhD in chemistry for his dissertation on the electron affinity of iodine and bromine. With support from the Rockefeller Foundation, Calvin pursued postdoctoral research at the University of Manchester in England under the esteemed physical chemist Michael Polanyi. There, he studied the paramagnetic conversion of hydrogen and the catalytic activity of metalloporphyrins.
Career and Scientific Research
Research at the University of California, BerkeleyIn 1937, Calvin returned to the United States and joined the University of California, Berkeley, as an instructor in chemistry. Under the mentorship of chemist Gilbert N. Lewis, he investigated the electronic nature of colored organic compounds.
During World War II, Calvin served as a research associate with the National Defense Research Council before participating in the Manhattan Project (1944-1945). He developed a method for generating pure oxygen from the atmosphere for industrial use.
In 1945, Calvin returned to Berkeley as an assistant professor, becoming a full professor two years later. In 1946, he was named director of the bio-organic chemistry division at the Lawrence Radiation Laboratory, a position he held until 1980.
His scientific interests centered on photosynthesis, the complex process by which green plants utilize sunlight to produce carbohydrates and oxygen from carbon dioxide and water. While the conditions and end products of photosynthesis had been established since Joseph Priestley's 1772 discoveries, the intermediate reactions remained unknown.
The Calvin Cycle
Calvin's research employed two novel analytical techniques. The first involved the use of carbon-14, a radioactive isotope of carbon. When assimilated by plants, it could be easily detected within organic compounds. Calvin enclosed Chlorella pirenoidosa, a green sea algae, in a thin glass cylinder (nicknamed "the lollipop" due to its shape) containing carbon dioxide enriched with carbon-14. The cylinder was illuminated, allowing the algae to interact with the labeled carbon dioxide and produce compounds involved in photosynthesis.
To identify the labeled compounds, Calvin used paper chromatography, a technique developed by Archer Martin and Richard Synge. In this method, components in a mixture are separated based on their differential migration along a strip of filter paper using different solvents. Each component forms a spot at a specific location on the strip, which can then be compared to the distribution of spots produced by known chemical reagents. To detect spots containing radioactive carbon, chromatography was used in conjunction with X-ray film, which darkens in the presence of any radioactivity.
"Unfortunately, the names of the compounds didn't print on the paper," Calvin later recalled. "So our laborious initial task for ten years was to patiently figure out what darkened spots on the film meant."
Through this painstaking work, Calvin and his team established that carbon dioxide initially reacts with ribulose diphosphate (a compound with a five-carbon backbone) to form phosphoglyceric acid, which is converted through a series of reactions into fructose-6-phosphate and glucose-6-phosphate. The steps involved in converting carbon dioxide into carbohydrates were termed the Calvin cycle and occur within the chloroplasts, specialized organelles within plant cells.
The Calvin cycle, which encompasses the "dark" reactions of photosynthesis, relies on high-energy compounds such as adenosine triphosphate and reduced nicotinamide adenine dinucleotide, which are generated during the "light" reactions involving the absorption of light by chlorophyll molecules.
Using radioactive isotopes, Calvin also traced the fate of oxygen in the photosynthetic reactions. For his "research on the assimilation of carbon dioxide by plants," Calvin was awarded the Nobel Prize in Chemistry in 1961.
Interdisciplinary Research and Later Career
Although recognized with a Nobel Prize in chemistry, Calvin's work was characterized by the intersection of disciplines, as chemistry, biology, and physics converged. He emphasized this aspect in his Nobel lecture:
"Chemical biodynamics, which involves the bringing together of many disciplines, will play a part in the solution of this problem [explaining the role of chlorophyll in energy conversion] just as it has in the elucidation of the carbon cycle. It will be increasingly important, it is to be expected, in the understanding of dynamic processes that occur on the molecular level in living organisms."
In 1963, Calvin became a professor of molecular biology and, in 1971, a professor of chemistry at the University of California, Berkeley. From 1960 to 1980, he served as director of the Laboratory of Chemical Biodynamics, where research spanned topics such as photosynthesis and solar energy conversion, radiation chemistry, brain chemistry, the molecular basis of memory, and the origin of life on Earth.
Using a cyclotron, Calvin bombarded carbon dioxide and hydrogen atoms, which transformed into molecules of amino acids and adenine, a component of nucleic acids. Discovering labeled organic matter in meteorites, he hypothesized the possibility of life elsewhere in the solar system.
Awards, Honors, and Legacy
Calvin received numerous honorary degrees and awards, including the Davy Medal from the Royal Society of London (1964), the Priestley Medal from the American Chemical Society (1978), the Gold Medal from the American Institute of Chemists (1978), and the Othmer Medal from the American Chemical Society (1981). He was a member of the Royal Society of London, the Royal Netherlands Academy of Arts and Sciences, the American Philosophical Society, the U.S. National Academy of Sciences, and the American Chemical Society (serving as its president in 1971).
Calvin's legacy as a pioneering scientist and advocate for interdisciplinary research continues to inspire generations of researchers. His groundbreaking work on the Calvin cycle has fundamentally shaped our understanding of photosynthesis and the role of plants in the Earth's ecosystem.
