Mildred Cohn

Mildred Cohn transformed the study of enzymes by aiming high-tech instruments at them. She had seen how powerful instruments dramatically improved other areas of scientific research. When the right instruments weren't available, she built her own.

In almost all of her research Cohn was interested in how chemical reactions take place, that is, how the molecules of each reactant come apart and how their atoms reassemble themselves into new molecules, and the role that enzymes play in this process. Cohn helped pioneer a technique called nuclear magnetic resonance, or NMR, and instruments like NMR spectrometers, which helped her to study how enzymes and other proteins behave during chemical reactions in the body.

About Her Life

Mildred Cohn was born in New York City in 1913. Her father had studied to be a rabbi but ended up an inventor. After leaving rabbinical school to work in a tailor shop, he invented a machine for cutting cloth more accurately, and his boss made him a partner in the business for this feat. Cohn would in time follow in her father’s footsteps as an innovator.

An especially bright child, Cohn started college when she was only 15, attending New York City's Hunter College, at that time a school for women. She loved physics but majored in chemistry because physics wasn't offered as a major at Hunter. One of her chemistry teachers told her it was "unladylike" for women to become chemists. Fortunately, she didn't listen to him, and it wouldn't be the last time she ignored a professor's advice.

Cohn wanted to go to graduate school, but by this time the Great Depression had hit. Her father's tailor shop went out of business and money was tight. She had saved some money for tuition, enough to take her as far as a master's degree in chemistry from Columbia University in 1932. But then her money ran out, and she went to work in a government aeronautics lab in Virginia to earn a living. After two years, she'd saved enough money to return to Columbia for her Ph.D. She asked to study under the great chemist Harold Urey, who had just won the Nobel Prize in Chemistry (1934). Urey tried to discourage her, saying that he didn't mentor his students very much and he expected them to teach themselves. Again, Cohn found herself ignoring a professor's advice and persisted. Urey finally gave in and let her join his research group.

Working for Urey, Cohn studied ways of separating different isotopes of carbon but ran into equipment trouble. Cohn ended up writing her dissertation on the behavior of isotopes of oxygen instead and graduated with her Ph.D. in physical chemistry in 1938.

Job hunting was hard because many ads she saw for chemists explicitly asked that applicants be male and Christian, putting two barriers of discrimination in the way of the young Jewish woman. But she did eventually find post-doctoral research work.

While most Ph.D. graduates work for two or three years in research before pursuing a professorship, Cohn ended up working as a researcher for more than 20 years. She first worked under biochemist Vincent du Vigneaud, another Nobel laureate, at George Washington University in Washington, D.C., and she went with Vigneaud when he moved to Cornell University in Ithaca, New York, in the late 1930s. Around this time, Cohn married Henry Primakoff, a physicist. She stayed at Cornell until 1946, when she left to work under the Nobel laureates Carl and Gerty Cori at Washington University in St. Louis, Missouri. Cohn became a professor in 1960, when she moved to Philadelphia to take a faculty position at the University of Pennsylvania.

Cohn retired in 1982 but has remained involved in the world of science and in the life of the University of Pennsylvania. After an active research career during which she also raised three children, she is remembered by her former students as a wonderful mentor and an important scientific innovator. She died in Philadelphia in 2009.