IMPLICATIONS OF N-TERMINAL AND C-TERMINAL PROXIMITY FOR PROTEIN-FOLDING

We have investigated the proximity of the N and C termini in protein s tructures, and developed a model to test the theoretical possibility t hat proteins fold with their termini closely associated. On average, t he distance between the termini is not significantly different from wh at would be expected based on chance. However, the theoretical model i ndicated that it is possible to greatly decrease the N-to-C terminal d istance by allowing small (approximately six amino acid residues) solv ent-accessible terminal fragments to move. Subsequent to this distance minimization method, more than 90% of the proteins studied had smalle r-than-expected N-to-C distances, but only minor structural modificati on. (C) 1996 Academic Press Limited