Figure 5.

Fundamental rules of designing proteins relating local backbone structures to favorable tertiary motifs.Left, ββ-rule, the chirality of β-hairpins is determined by the length of the connecting loop. The chirality is defined on the basis of the pleat of the strand residue preceding or following the connecting loop. Middle, βα-rule, the helix direction is determined by the pleat direction of the last strand residue and the length of the connecting loop. Right, αβ-rule, the pleat of the first strand residue points away from the helix (39). Figure provided by Dr Nobuyasu Koga (Institute of Molecular Science, Japan).