I'm trying to refine a cryoEM structure that contains some MAN/C1-TRP/CD1 glycosylations. I've done this successfully in crystallographic reciprocal space refinement, using cif files to define the MAN geometry and the MAN-TRP linkage, plus adding LINK instructions to the pdb file. In this cryoEM structure, though, using the same .cif definition files and similar LINK instruction, the bond is still not defined in the .geo file and instead it's treated as a nonbonded interaction, kicking the mannose away from the indole side chain. The NAG-ASN linkages in the cryoEM structure are fine. Do I need to do anything differently to define these linkages in Real Space Refine compared to phenix.refine?
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Kevin Jude, PhD (he/him/his)
Structural Biology Research Specialist, Garcia Lab