Hi all,

I have a case where we have crystallised a ligand in our protein and the ligand purchased is a mixture of 4 structural isomers (enantiomers and diastereomers). There is no way of telling if one over the other is bound in the active site  so we have assumed all 4 are binding. I have generated 4 separate ligands with 4 separate cifs and the all fit the density. I am refining the complex with all 4 ligands at 0.25 occupancy (occupancy refinement is switched off, I have changed the clash guard non-bonded distance threshold is set to 0.0 (as an initial error message came up with nonbonded interactions < 0.5).

My refinement ran to completion, but something is definitely not right. The pdb file won’t load in Coot and in pymol the ligands have imploded/exploded. I am just wondering if this is the best way to refine this structure (or I have missed something) and probably more to the point what have I missed with the ligands. To me it is almost identical to alternate conformations, but I have obviously missed something

I have just install phenix 1.10 on a windows machine.

Thanks

J

_________________________________

Joel Tyndall, PhD

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

Skype: jtyndall

Ph: +64 3 479 7293