A dodecacyclopeptide, which was used as a supporting template in template assembled synthetic approach for four-helix-bundle proteins, was studied by solution 2D-NMR and distance geometry calcns. All hydrogen atoms in the mol. were assigned by anal. of its 2D-COSY and NOESY spectra. DIANA distance geometry calcns. were carried out with 62 interat. distances derived from NOE cross peak intensities. Among the 100 structures obtained, the top 10 structures with lowest target function values were selected as final results. The main chain atom r.m.s. between this 10 structures was 0.029 ?0.006nm, showing very rigid conformation of the dodecacyclopeptide mol. The four lysine side chains used as attaching points for four helix were found facing towards the same side of the cyclopeptide ring, showing the validity of utilizing this dodecacyclopeptide in the synthesis of four-helix-bundle proteins.