Alpha-helix mimicry of a beta-turn.

It is shown here that the three-dimensional arrangement of the amino acids in an RGDF beta-turn (sequence involved in cell adhesion) resembles that of an alpha-helix with a shuffled RGDF sequence (i.e. RGXFD). A miniprotein was designed and constructed which arranges the RGXFD sequence into a well defined helical conformation. The designed protein is bioactive and folds into the desired structure as assessed by nuclear magnetic resonance spectroscopy. The recognition process mediated by a beta-turn can thus be mimicked by an alpha-helix.