The structural prototype of a new generation of regioselectively addressable functionalized templates (RAFTs) for use in protein de novo design has been synthesized and crystallized. The structure of the aromatically substituted cyclodecapeptide was determined by X-ray diffraction; it consists of an antiparallel beta sheet spanned by heterochirally induced type II' beta turns, similar to that observed in gramicidin S The three-dimensional structure of the artificial template was also examined by an NMR spectroscopic analysis in solution and shown to be compatible with a beta -sheet plane suitable for accommodating secondary functional peptide fragments for the synthesis of template-assembled synthetic proteins (TASPs).