have a look in the ccp4bb archives, this has been discussed multiple times 
without a clear conclusion

my approach would be to keep them and let the B-factors refine to high values, 
the reason is that you know the side-chains are there and with full occupancy
(the validation statistics may be worse but that is normal for low-res 
structures)


Mark van Raaij
Dpto de Estructura de Macromoleculas, lab B5B
Centro Nacional de Biotecnologia - CSIC
calle Darwin 3
E-28049 Madrid, Spain
tel. +34 91 585 4616 (internal 432092)



> On 2 Jul 2026, at 16:47, Martin Hu 
> <[email protected]> wrote:
> 
> Dear all,
> 
> I would like to ask for some advice on the best way to handle poorly defined 
> side chains for deposition of a low-resolution (~3.6 Å) X-ray structure.
> 
> For a number of residues in my structure, there is little or no side-chain 
> density, so I do not feel confident modelling the full side chains. At the 
> moment, I have deleted the residues that are not supported by the electron 
> density, which also gives better geometry and refinement statistics.
> 
> I asked the PDBe deposition team whether they had any preference between 
> deleting the unsupported side-chain atoms or keeping them with zero 
> occupancy. They replied that they do not have any specific requirements, as 
> long as the deposited model is appropriate.
> 
> I was therefore wondering how people here would normally deal with this 
> situation for PDB deposition. Would you generally:
> 
> * delete the unsupported side-chain atoms,
> * keep the full side chains but set the unsupported atoms to zero occupancy,
> * or use another approach?
> 
> I’d be interested to hear what people usually do for structures around this 
> resolution.
> 
> Many thanks in advance.
> 
> Best regards,
> 
> Martin Hu
> 
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