[Xplor-nih] Problems constraining a guanine residue to syn conformation

[yu269821 at yorku.ca]

Hello,

I am calculating RNA structures using the 2.16.0 version of XPLOR-NIH.
I am using parallhdg.dna as my parameter file. I am having trouble
constraining a guanine residue to a syn conformation. Normally one
intranuclear restraint (H8 to H1' constrained to 2.15 0.35 0.65) should
be sufficient, however this restraint keeps being violated even if
that is the only restraint used for that residue (I also have no hydrogen
bonding, dihedral angles planarity restraints for that residue) in
about half of my structures. Can this be a problem with my parameter
file may be something else?

Thank you in advance,
Alex Beribisky.