Orthogonal beta beta motifs in proteins.

A super-secondary structural motif comprising two orthogonally oriented beta-strands connected by short linking segments of less than or equal to 5 residues has been identified from a data set of 65 independent protein crystal structures. Of the 42 examples from 14 proteins, a vast majority have only a single residue as the linking element. Analysis of the conformational angles at the junction reveals that the recently described type VIII beta-turn occurs frequently at the connecting hinge, while the type II beta-turn is also fairly common.