COMPARISON OF THE ACCURACY OF PROTEIN SOLUTION STRUCTURES DERIVED FROM CONVENTIONAL AND NETWORK-EDITED NOESY DATA

Network-editing experiments are variants of the basic NOESY experiment that allow more accurate direct measure ment of interproton distances in macromolecules by defeating specific spin-diffusion pathways. Two network-editing approaches, block-decoupled NOESY and complementary-bl ock-decoupled-NOESY, were applied as three-dimensional, heteronuclear- edited experiments to distance measurement in a small protein, turkey ovomucoid third domain (OMTKY3). Two-hundred and twelve of the origina l 655 distance constraints observed in this molecule (Krezel AM et al. , 1994, J Mol Biol 242:203-214) were improved by their replacement by distances derived from network-edited spectra, and distance geometry/s imulated annealing solution structure calculations were performed from both the unimproved and improved distance sets. The resulting two fam ilies of structures were found to differ significantly, the most impor tant differences being the hinge angle of a beta-turn and an expansion of the sampled conformation space in the region of the reactive-site loop. The structures calculated from network-editing data are interpre ted as a more accurate model of the solution conformation of OMTKY3.