Hello Jian-- > We are calculating the structure of a membrane peptide with two > helices linked with a loop with PISEMA data (chemical shift, dipolar > coupling) with dihedral angleļ¼ hydrogen bond restraints for the > helical part, we also have some distance restraints for atoms from > both helices. > > From PISEMA experiment we expect to get models with the right tilt > angle with respect to the membrane normal (i.e., the z-axis), but we > got models with a variety of tilt angles. For example, we expect to > have a tilt angle of 12 to 17 degrees, but some of the models have > tilt angle that is 26, which is way too large. > I'm wondering what are the factors that determine the tilt angle of > the peptide in XPLOR calculation.
Are your restraints well-satisfied? There may be some problem such that there are large violations causing convergence problems. If your PISEMA-based restraints are satisfied, then the tilt angle should be correct. No? best regards-- Charles
-- Charles Schwieters email: [email protected] www: http://schwieters.org/cds phone: (301) 402-4914 PGP key: http://schwieters.org/cds/pgp.txt
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