Marjory Stephenson - Research at Cambridge

Research At Cambridge

After the end of the war, Stephenson returned to Cambridge to carry out research and teach in the department of biochemistry. Under the leadership of Frederick Gowland Hopkins, a group of scientists became the centre of modern biochemical studies. Here Stephenson began research on bacteria and their metabolism. The department had an unusually high proportion of women amongst its researchers (15 per cent), but it was still very rare for a woman to be offered a University appointment. Stephenson was financed by her Beit Fellowship and later by the Medical Research Council. She was finally appointed a University lecturer in biochemistry in 1943. Meanwhile she became an associate and later a fellow of her old College, Newnham. In 1936 the University awarded her an ScD degree for her research.

Stephenson's main area of research was bacterial metabolism. With Margaret Whetham and Juda Quastel, she developed the washed suspension technique, which had originated with Louis Pasteur, for extracting enzymes from bacteria. With Leonard Stickland, she was the first to isolate a bacterial enzyme from the cell in 1928, when they obtained lactic dehydrogenase from Escherichia coli. In the 1930s, she continued to work with Strickland and demonstrated that a particular enzyme, formate hydrogenlyase, was present in cell extracts only when the bacteria had been grown in the presence of formate. This was one of the first examples of 'adaptive enzymes.' (This is now understood as the rapid transcriptional activation of the gene encoding the formate hydrogenlyase when the inducer molecule, formate, is added to the culture). Later in the 1930s Stephenson worked with Ernest Gale on enzyme adaptation and amino acid metabolism, and with Arthur Trim on metabolic studies of nucleic acids.

During her time at the laboratory, Stephenson produced, as author or co-author, more than twenty papers. She is most widely remembered for her seminal book, Bacterial Metabolism, which ran to three editions between 1930 and 1949. Last reprinted in 1966, it was the standard work on the subject for generations of microbiologists and biochemists.