The Woman Who Unraveled the Mysteries of Soy

“An Israeli scientist makes worldwide headlines for discovering a new hormone,” announced the daily newspaper Ma'ariv in April 1964. “Yehudith Birk, the young (37) scientist, is a handsome, pleasant, lovely and good-spirited woman. She is married and a mother of two boys,” says the body of the article, written by Ada Cohen. “A stylish dress peeks from under her ‘formal’ lab coat… and she has every appearance of a socialite. Only… a little bit cleverer.”

Yehudith Gershtanski was born on September 30, 1926, in Grajewo, Poland, an only child to a merchant father and an accountant mother, who was active in establishing Hebrew schools in their city. Her daughter also studied at these schools, until the family made Aliya in 1935. The family rented an apartment in Tel-Aviv, where nine-year-old Yehudith befriended the landlord's son, Meir Birk, who was two years her senior.

She studied at the High School for Commerce, where she excelled not only in her studies, but also as an athlete and a basketball player for Maccabi Tel-Aviv. After graduation, she did one year of civil service in Kibbutz Alonim, and in 1945, began studying biology and chemistry at The Hebrew University of Jerusalem. Her high-school literature teacher, who had high hopes for her, travelled especially to Jerusalem in an attempt to persuade her to switch to literature. But Yehudith stuck with science.

Forced to stop her studies when the War of Independence broke, she enlisted in the IDF's Science Corps. On the Israeli Academy of Sciences website, Lea Tzivoni describes how Birk's service in the IDF involved manufacturing flares. She performed experiments, during which she threw the flares over the sea from a Piper plane with no door. Holding on to her plane seat with one hand, she hurled the flares with the other to test if they were functioning and if their parachute would open.

Before joining the army, she married Meir Birk, then a physics student at the Technion who had also joined the Science Corps. Returning to her studies in Jerusalem after the war, Birk received a Master's degree in biochemistry and microbiology in 1950. With encouragement from her husband, she decided to pursue a PhD in biochemistry at the Agricultural Experimental Station in Rehovot.

Under the mentorship of Aron Bondi from the Department of Animal Nutrition, she researched a relatively new field – plant proteins – studying the nutritional value of soy proteins. She completed her PhD in 1953 and continued working at the Experimental Station, which, in the meantime, became the Hebrew University's Faculty of Agriculture. Her husband, Meir, joined the scientific establishment across the street – the Weizmann Institute of Science. The family, which grew over time with the birth of their two children, settled in Rehovot.

Scientific achievements. The Ma'ariv story on Birk's scientific work. 1964

Hormones and proteins

In 1955, Birk went to the United States for her postdoctoral training in the laboratory of Selman Waksman, a Nobel Prize in Medicine laureate who developed antibiotics, at Rutgers University. Rejecting numerous offers to remain in the United States, she returned to the Faculty of Agriculture – and to soy proteins, which she continued to investigate as an independent researcher.

In 1962, the family was in the United States again, for a sabbatical at the University of California, Berkeley. Working with hormone researcher Prof. Choh Hao Li, Birk now focused on pituitary-gland hormones and her experience in protein research enabled her to perfect their fractionation methods. These advanced methods facilitated her discovery of the hormone responsible for fat break-down – beta lipoprotein.

“This hormone opened new possibilities for the development of a fat-dissolving drug,” Ma'ariv quoted international scientists saying. Birk, however, said to the journalist, that after finding evidence that the hormone has an effect on lab animals, “the road from mouse to human is long; even if they show that the substance is good for dissolving fat, it is still not clear how a drug would be formulated from it.” Later, this hormone was found to be a precursor of natural painkillers in the body, endorphin and enkephalin, so its importance is even greater than previously thought.

Once again, Birk politely declined offers to stay in the United States (“Responsibility is responsibility and an Israeli need to know where he stands,” reads the Ma'ariv article), and returned to her studies of soy proteins at the Faculty of Agriculture. Her research now focused on a certain protein that inhibits the breakdown of other proteins. She identified a common mechanism for a group of protease inhibitors found in many legumes, which are now termed “Bowman Birk Inhibitors,” named after her and after Prof. Donald Bowman, who discovered the protein.

Bowman Birk Inhibitors protect plants from potential pests by neutralizing the activity of the enzymes trypsin and chymotrypsin. Many years of research into the properties of these proteins paved the way for their application as natural pesticides for agricultural products in the field and in storage, as nutrients, and even as possible drugs for certain types of cancer.

Birk was among those responsible for laying the research infrastructure of the Faculty of Agriculture. Among her other activities, she founded the School of Nutritional Sciences in 1972 and headed it. She also headed the Faculty’s Department of Biochemistry and was later appointed as Dean of the Faculty of Agriculture – the first woman ever to serve as a dean at the Hebrew University.

Birk was very active in promoting science and science education and was also a member of the council of the Wolf Foundation, which grants awards and scholarships to excelling scientists and students. She received many honors and prizes for her scientific work, most notably, the Israel Prize in Agriculture in 1998. She passed away in 2013, at the age of 86.

Israel Prize laureate and one of the founders of research at the Faculty of Agriculture. A sign on the street named after her in Rehovot 

Translated by Elee Shimshoni