THE FEATURES OF THE SPATIAL STRUCTURE OF THE GRAMICIDINE A-CESIUM COMPLEX

Earlier obtained two-dimensional H-1-NMR spectroscopy data were used t o analyze the spatial structure and conformational mobility of the dou ble right up down arrow pi pi(LD)(7.2) helix of the complex formed by gramicidine A and Cs+ ions in an organic solvent (a chloroform-methano l mixture). Analysis of the experimental data permitted the determinat ion of a set of conformations for each of the high-mobility residue si de chains in the solution. The energy refinement of the most probable conformation of the double right up down arrow pi pi(LD)(7.2) helix wa s made and conformational rearrangements of the tryptophan residue sid e chain were studied in detail.