Biography:John Read Cronin
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John Read Cronin (August 3, 1936 – June 30, 2010) was an American biochemist and organic geochemist known for his research in the field of meteoritic organic chemistry. His work advanced the understanding of the role of extraterrestrial organic molecules in the origin of life.
Early life
Education
Career
Cronin's research explored the organic chemistry of meteorites, with a specific focus on carbonaceous chondrites like the Murchison meteorite. His work provided insights into the diversity and complexity of extraterrestrial organic compounds and their potential role in the origin of life on Earth. John worked closely with Sandra Pizzarello with whom he collaborated extensively.
The meteorite center explained the significance of Cronin's findings and contributions.[1] As the world consensus at the time was skeptical about the presence of amino acids in meteorites, John Cronin and his colleagues conducted independent tests using different analytical techniques to detect amino acids in various meteorites, including Murchison, Murray, and Allende. Their findings showed that:
- Murchison and Murray contained amino acids, while
- Allende did not, proving that contamination wasn't an issue.
This led Cronin and his team to further study the organics present in meteorites. They identified various compounds, including carboxylic acids, complex amino acids, and aliphatic hydrocarbons also using nuclear magnetic resonance.
The team also collaborated with Samuel Epstein from Caltech to examine the isotopic signatures of organic molecules in meteorites, which further supported their extraterrestrial origin. Cronin and Sandra Pizzarello discovered the asymmetry of organic molecules before they fell to Earth, which might have originated from the interstellar medium. This research is significant because the exclusively left-handed nature of life's molecules is essential for the structures and functions of terrestrial biopolymers and is assumed to be crucial for the emergence of life.
Research contributions
Organic compounds in meteorites
Cronin's analysis of carbonaceous chondrite meteorites revealed a rich diversity of organic molecules, including amino acids, hydrocarbons, and nucleobases. His research demonstrated that these meteorites contain complex organic compounds that could have been significant in prebiotic chemistry.[2]
Chirality and enantiomeric excess
Cronin's research on the chirality of meteoritic amino acids provided evidence of non-racemic mixtures, suggesting a potential extraterrestrial source of chiral asymmetry. This finding has implications for the development of homochirality in biological molecules on Earth.[3]
Isotopic composition of organic molecules
Cronin conducted isotopic analyses of meteoritic organic compounds, revealing distinct isotopic compositions that supported their non-terrestrial origin. This work provided insights into the extraterrestrial sources of prebiotic molecules. They investigated and published significant work on the Murchison meteorite.[4]
Impact chemistry and prebiotic synthesis
Cronin's research explored how meteorite impacts could synthesize organic compounds from simpler precursors, highlighting the potential role of impact-generated environments in prebiotic chemistry.[5]
References
- ↑ "History – Buseck Center for Meteorite Studies". https://meteorites.asu.edu/aboutus/history.
- ↑ Cronin, John R.; Chang, Sherwood (1993). "Organic Matter in Meteorites: Molecular and Isotopic Analyses of the Murchison Meteorite". The Chemistry of Life's Origins. pp. 209–258. doi:10.1007/978-94-011-1936-8_9. ISBN 978-94-010-4856-9.
- ↑ Cronin, John R.; Pizzarello, Sandra (14 February 1997). "Enantiomeric Excesses in Meteoritic Amino Acids". Science 275 (5302): 951–955. doi:10.1126/science.275.5302.951. PMID 9020072. Bibcode: 1997Sci...275..951C.
- ↑ Pizzarello, Sandra; Cronin, JR (1998). "Alanine enantiomers in the Murchison meteorite". Nature 394 (6690): 236. doi:10.1038/28306. PMID 9685155. Bibcode: 1998Natur.394..236P.
- ↑ Cronin, John R.; Pizzarello, Sandra (October 1996). "Enantiomeric analyses of chiral organic compounds from the Murchison meteorite". Origins of Life and Evolution of the Biosphere 26 (3): 248. doi:10.1007/BF02459738. Bibcode: 1996OLEB...26..248C.
External links
- Arizona State University (https://search.asu.edu/profile/47413)
- Obituary (https://www.legacy.com/us/obituaries/azcentral/name/john-cronin-obituary?id=22397144)
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