Jane Richardson's ribbon diagrams

Proteins are minuscule, on the order of nanometers, and can contain hundreds of thousands of atoms. “If those atoms are all drawn and then joined together, it becomes very difficult to see,” Thornton said.

Richardson’s innovation was a reproducible method of representing the folds of a protein’s amino acid backbone without getting bogged down in the details of specific atomic arrangements. 

She relied on proteins’ tendency to fold into two energetically favorable shapes: coils called alpha helices and flat shapes called beta strands, which can line up into so-called beta sheets. Then there are loops, which connect alpha helices to beta strands like corner pieces in a puzzle.

There are other folding structures, and “people have come up with lots of names” for them, Perrakis said. “But at the end of the day, the ones that matter are the helices and the sheets.”