H ithere,

I am trying to refine a covalently bound ligand to my protein and I am having trouble with the restraints. I have generated the cif file and link within Jligand and this is reasonable. However it appears that REFMAC is overriding these and fitting the ligand to the density.

I have added a keyword text file with externtal restraints such as :

exte angle first chain A resi 1 atom S12 second chain A resi 1 atom C10 third chain A resi 2 atom N value 120 sigma 3.0

The resulting structures has incorrect angles which do not match the external restraints or cif file. Am I missing something?

Any help muchly appreciated. (I am using the most upto date version of the CCP4 package on a PC)

Joel

_________________________________

Joel Tyndall, PhD

Senior Lecturer in Medicinal Chemistry
National School of Pharmacy
University of Otago
PO Box 56 Dunedin 9054
New Zealand  

Skype: jtyndall
http://www.researcherid.com/rid/C-2803-2008

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