Since 1960s we know that protein's three-dimensional structure is determined by its amino acid sequence (today we also know that sometimes help from "chaperone" proteins is needed during folding). Predicting the shape of the protein (tertiary structure) based only on the amino acid sequence (primary structure), however, was a daunting task. As said above, the next step after solving the folding problem will be understanding how proteins work in generally, predicting the interactions and characteristics of the protein, knowing its 3d shape.