β-bulges can be grouped according to their length of the disruption, the number of residues inserted into each strand, whether the disrupted β-strands are parallel or antiparallel and by their dihedral angles (which controls the placement of their side chains).
β-bulges can be sorted according to the extent of disruption, the quantity of residues placed between strands, the orientation of the disrupted β-strands as either parallel or antiparallel, and by their dihedral angles (which influence the arrangement of their side chains).