The three-dimensional structure of the chemotactic peptide N- formyl- l -Met- l -Leu- l -Phe-OH was determined by using solid-state NMR (SSNMR). The set of SSNMR data consisted of 16 13 C– 15 N distances and 18 torsion angle constraints (on 10 angles), recorded from uniformly 13 C, 15 N- and 15 N-labeled samples. The peptide's structure was calculated by means of simulated annealing and a newly developed protocol that ensures that all of conformational space, consistent with the structural constraints, is searched completely. The result is a high-quality structure of a molecule that has thus far not been amenable to single-crystal diffraction studies. The extensions of the SSNMR techniques and computational methods to larger systems appear promising.
