Mildren Cohn (1913–2009)

Mildren Cohn overcame gender and religious prejudice to leave a profound impact on biochemistry and biophysics. Among the first scientists to apply electron spin and nuclear magnetic resonance (NMR) to investigate metabolism, she pioneered the use of NMR to determine how enzymes and other proteins behave during chemical reactions in the body.

Cohn started college in 1928 when she was only 15, majoring in chemistry at Hunter College in New York because physics wasn’t available. One chemistry teacher at the all-women’s college told her it was “unladylike” for women to become chemists. Three years later, she graduated cum laude and left with a determination to pursue graduate education in the physical sciences.

She joined the doctoral program at Columbia but was barred from teaching assistant positions, which were awarded only to men. In 1932, she earned a master’s degree in chemistry then returned to Columbia two years later seeking a Ph.D. with a special request to study under Harold Urey, who had just won the Nobel Prize in chemistry (1934). Under Urey, Cohn studied ways of separating different isotopes of carbon. (Isotopes are atoms that contain the same number of protons but a different number of neutrons.) Due to equipment trouble, she ended up writing her dissertation on the behavior of isotopes of oxygen instead, for which she was awarded a Ph.D. in physical chemistry in 1938.

Like many graduate students, Cohn applied for industrial positions. As a Jewish woman, she could not get an interview with large companies that explicitly advertised for male, Christian applicants. Eventually, she won a postdoctoral position with Nobel laureate Vincent du Vigneaud at George Washington University in Washington, D.C. Vigneaud wanted to introduce isotopic tracers (a form of chemical elements) into his research on sulfur-amino acid metabolism. Cohn was able to gain a clear understanding of the mechanisms of chemical reactions in animals. For example, she observed the mechanism by which methionine was converted to amino acid cystine in rats.

In the late 1930s, she followed Vigneaud to Cornell University in Ithaca, New York. Around this time, Cohn married Henry Primakoff, a physicist. She stayed at Cornell until 1946, when her husband received a faculty appointment at Washington University in St. Louis, MO, where Cohn joined the biochemistry laboratory run by the new Nobel laureates Carl and Gerty Cori.

Mildred Cohn
My career has been affected at every stage by the fact that I am a woman, beginning with my undergraduate education…My greatest piece of luck was marrying Henry Primakoff, an excellent scientist who treated me as an intellectual equal and always assumed that I should pursue a scientific career and behaved accordingly.

Her major assignment was to study reactions to acceleration of chemical changes in enzymes (enzyme catalysis). Cohn used an isotope of oxygen to gain insight on organic phosphates. In 1958, she began working with nuclear magnetic resonance — a phenomenon that occurs when the nuclei of certain atoms in a static magnetic field are subjected to a second oscillating electromagnetic field in the form of radio frequency radiation, which causes the nucleus to resonate (or assemble in pattern).

Two years later, she took a position in the University of Pennsylvania’s biophysics department. She pursued research on how energy changes in cells and cellular reactions where adenosinetriphosphate (ATP) – a compound that transports chemical energy within cells for metabolism – is used, employing NMR to probe chemical structures. Her methods for looking more deeply into the structure and function of enzymes and other molecules, structures, and reactions are now widely practiced by other scientists to study metabolic processes at the molecular level.

Cohn became a full professor at the University of Pennsylvania in 1960, more than 20 years after receiving her Ph.D. She was the first woman to be appointed to the board of the Journal of Biological Chemistry, where she served as editor for 10 years (1958-63; 1968-73).

From 1978 to 1979, Cohn was president of the American Society of Biological Chemistry. She retired in 1982 from Penn, the same year that she received the National Medal of Science. A member of the National Academy of Science, she has been granted honorary doctorates from nine universities. Cohn died of pneumonia in 2009.


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  4. Scudel, Matt. (2009). Scientist overcame bias to excel in biochemistry and biophysics. The Washington Post. Retrieved from

NMR Dedicated a National Historic Chemical Landmark

The revolutionary technique that gives scientists a fast, nondestructive, noninvasive method of observing the detailed structure of molecules as they synthesize was dedicated a National Historic Chemical Landmark on March 11, 2011 at the Stony Brook University Department of Chemistry in Stony Brook, New York.