Ada E. Yonath (Hebrew: עדה יונת, pronounced [ˈada joˈnat]; born 22 June 1939)[1] is an Israeli crystallographer and Nobel laureate in Chemistry, best known for her pioneering work on the structure of ribosomes.

While a postdoc at MIT she spent some time in the lab of subsequent 1976 chemistry Nobel Prize winner William N. Lipscomb, Jr. of Harvard University where she was inspired to pursue very large structures.

Yonath focuses on the mechanisms underlying protein biosynthesis, by ribosomal crystallography, a research line she pioneered over twenty years ago despite considerable skepticism of the international scientific community.

[20] Ribosomes translate RNA into protein and because they have slightly different structures in microbes, when compared to eukaryotes, such as human cells, they are often a target for antibiotics.

Consequently, she showed that the ribosome is a ribozyme that places its substrates in stereochemistry suitable for peptide bond formation and for substrate-mediated catalysis.

Additionally, Yonath elucidated the modes of action of over twenty different antibiotics targeting the ribosome, illuminated mechanisms of drug resistance and synergism, deciphered the structural basis for antibiotic selectivity and showed how it plays a key role in clinical usefulness and therapeutic effectiveness, thus paving the way for structure-based drug design.

For enabling ribosomal crystallography Yonath introduced a novel technique, cryo bio-crystallography, which became routine in structural biology and allowed intricate projects otherwise considered formidable.