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Hello Andrew-- > I'm running RDC refinement on the NMR structures of several > glycopeptides, and in some of the resulting accepted structures the > Rhombicity (which, along with Da was allowed to float during the entire > SA run) will consistently hit either the upper (0.667) or lower (0.0) > limits, as reported in the pdb file for the resulting structure. This > indicates to me that there is something wrong with my RDC restraints. > Perhaps an RDC restraint on a residue that is experiencing a certain > amount of conformational averaging? Da values all look reasonable. > When the Rhombicity does hit one of the limits, it will only hit the > upper or only the lower limit, but not both for the same construct. Any > thoughts as to what this could be? Rhombicity values of 0 and 2/3 are quite valid. You might double check the consistency of the value by back-calculating the alignment tensor using calcTensor after the calculation. You might also run calcDaRh to get a structure-independent value of rhombicity. Also, when allowing Da and Rh to float during a calculation- carefully look at the Da/Rh convergence. best regards-- Charles -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Processed by Mailcrypt 3.5.8+ <http://mailcrypt.sourceforge.net/> iD8DBQFIm01zPK2zrJwS/lYRAgsmAJ40lKw9IgvYytfxWel+0fiGc0RVNACdG7BK Uo1RvhD50ZCD35DaVESrDMo= =967f -----END PGP SIGNATURE-----
