NMR AND DYNAMICAL SIMULATED ANNEALING STUDIES ON THE SOLUTION CONFORMATION OF UROTENSIN-II

We determined the structure in solution of the vase-constrictor hormon e urotensin II (dodecapeptide) using nuclear magnetic resonance spectr oscopy. Complete assignment of all proton resonances has been achieved and the structural information has been obtained from the interproton distance measurements derived from the nuclear Overhauser enhancement data. A combination of distance geometry and dynamical simulated anne aling techniques was used to calculate the structure in solution. Nine resultant structures with fewer distance constraint violations were s elected that satisfy the experimental restraints very well. The confor mation of the molecule in the cyclic hexapeptide segment (core region) is well-defined whereas the N-terminal segment is disordered. This re sult correlates very well with the earlier predictions about the biolo gically active and inactive roles played by the core and the N-termina l segment respectively.