The Protein Folding Problem

Proteins are life's machinery — antibodies that grip viruses, enzymes that build molecules, channels that gate cells. Each one is manufactured as a linear chain of amino acids, drawn from an alphabet of just 20, and each chain spontaneously crumples into a precise three-dimensional shape.

The shape is everything: it determines what the protein grabs, cuts, or carries. Anfinsen won a Nobel Prize for showing that the sequence alone dictates the fold — the information for the machine is fully written in the chain. So the problem sounds computable: given a sequence of letters, predict the 3D coordinates. Fifty years of effort said otherwise.