On Jan 3, 2006, at 10:11 a, Kevin Karplus wrote: > > The debate over whether to include torsion angles in determining > secondary structure is an old one (DSSP vs. STRIDE). It turns out > that on high-quality x-ray structures it doesn't make much difference > what algorithm you use---the disagreements come down to matters of > opinion about where the edges of secondary structures are. The > biggest differences are on NMR structures, where insufficient data or > insufficient refinement often results in failure to get Hbonds within > the recognition range of algorithms like DSSP. Then using the phi and > psi angles can help compensate for the noisy positions of the donor > and acceptor atoms. > hi Kevin, thanks for the clarification. how would you define a 'high-quality' x-ray structure? is there a generally accepted threshold for resolution or RMSD? regards, tim -- Timothy Driscoll em: molvisions at mac.com molvisions - see. grasp. learn. ph: 919-368-2667 <http://www.molvisions.com/> im: molvisions usa:virginia:blacksburg tx: molvisions at vtext.com