Recurring substructures

Frequently recurring substructures or folds are collectively termed supersecondary structures or motifs. These are combinations of a and/or j8 structure. A simple example is a /8 hairpin, consisting of two antiparallel strands joined by a loop of three to five residues (Figure 1.12). This frequently occurs in antiparallel P sheet. Such sheet frequently contains four p strands connected as in Figure 1.13 in a motif called a Greek key (or meander, which is the Greek word for the pattern) because it is reminiscent of the Greek decorative motif, or six strands described as a jellyroll. 

File Enrichment Strategies with Recurring Substructures I 21... 

---