André Tridon Jagendorf was born on October 21, 1926 in New York City to Moritz Adolph Jagendorf and Sophie Sheba Jagendorf. He married Jean Elizabeth Whitenack on June 12, 1952. They had three children Suzanne, Judith and Daniel ; 8 grandchildren; and 9 great grandchildren. André Jagendorf died on March 13, 2017.
University life
André Jagendorf graduated from Cornell University where he was strongly influenced by Loren Petry who taught General Botany. He earned his PhD in 1951 at Yale University under David Bonner. André then went to UCLA, where he was awarded a Merck Postdoctoral fellowship and spent what he called "the happiest years of my life" working with Sam Wildman. Jagendorf became an Assistant professor at Johns Hopkins University in 1953, as Associate professor in 1958, and a Full professor in 1966. Jagendorf then returned to Cornell University as Professor of Plant Physiology, and in 1981 became the Liberty Hyde Baily Professor. Since 1997 Jagendorf has been the Liberty Hyde Bailey Professor Emeritus in the Department of Plant Biology and was actively doing research until days before his death.
Research
Jagendorf heard Peter Mitchell give a talk about chemiosmosis at a bioenergetics meeting in Sweden. According to Jagendorf, "His words went into one of my ears and out the other, leaving me feeling annoyed they had allowed such a ridiculous and incomprehensible speaker in. But – Geoffrey read Nature. Geoffrey was from England, both better trained and more intelligent than I was. He read Peter Mitchell’s paper, came to me, and said ‘André, could this possibly explain XE ?’" As a result of this conversation, Jagendorf began to communicate with Peter Mitchell who invited him to visit his lab so that he could learn about the chemiosmotic hypothesis. Later that summer Jagendorf did the experimentum crucis that showed that the synthesis of adenosine trisphosphate by chloroplasts depended on the magnitude of the pH difference. The experiment consisted of creating a pH gradient across the thylakoid membrane of chloroplasts in the dark. Jagendorf and Uribe created the transient pH gradient by incubating chloroplasts in a pH 4 buffer for 15 seconds. They then placed the chloroplasts in a pH 8 buffer that contained ADP and Pi. Under these conditions, the pH of the stroma increased to 8, whereas the pH of the thylakoid lumen remained at 4. An immediate increase in ATP synthesis accompanied the dissipation of the pH gradient across the thylakoid membrane. According to Berg et al. "This incisive experiment was one of the first to unequivocally support the hypothesis put forth by Peter Mitchell that ATP synthesis is driven by proton-motive force." Following Jagendorf's results, Mitchell wrote a letter to Edward C. Slater on November 2, 1965, stating: "experiments have been steadily pushing me towards accepting the chemiosmotic hypothesis and I think I shall feel inclined presently to regard it as a theory." Jagendorf was also a pioneer in many aspects of chloroplast molecular biology, including DNA repair mechanisms.
