PROTEIN FOLDS IN THE ALL-β AND ALL-α CLASSES

Analysis of the structures in the Protein Databank, released in June 1996, shows that the number of different protein folds, i.e. the number of different arrangements of major secondary structures and/or chain topologies, is 327. Of these folds, approximately 25% belong to the all-α class, 20% belong to the all-β class, 30% belong to the α/β class, and 25% belong to the α + β class. We describe the types of folds now known for the all-β and all-α classes, emphasizing those that have been discovered recently. Detailed theories for the physical determinants of the structures of most of these folds now exist, and these are reviewed.