I have a structure with an unsaturated lipid in the active site, which
according to the chemists has one cis and one trans double bond. I
would expect these to be controlled by the torsion angles in the cif
files. However altering torsions between 0 and 180 makes no difference
to the refinement and I get back what I put in terms of the fit of the
molecule in coot. Coot is great for fitting such molecules into the
density, but you can flip the cis-trans fairly easily.
Is it correct that I just have to make sure the bonds are correct before
starting refinement as the energy penalty for a cis/trans bond being
wrong despite the torsion being set to a constant is simply too small?
Best wishes
Nick
--
Dr Nicholas H. Keep
Dean of Faculty of Science
Reader in Structural Biology
School of Crystallography,
Birkbeck, University of London,
Malet Street,
Bloomsbury
LONDON
WC1E 7HX
email [EMAIL PROTECTED]
Telephone 020-7631-6852 (Room G57 Office)
020-7631-6868 (Rosalind Franklin Laboratory)
020-7631-6800 (Department Office)
Fax 020-7631-6803
If you want to access me in person you have to come to the
crystallography entrance
and ring me or the department office from the internal phone by the door
