The first thing you want to consider is Resolution.

Lower the better.

Dear Wiilberforce Ndarawit Please consider the points mentioned by the Iqra Aroob Iqra Aroob and the below-mentioned points.

PDB Selection criteria:

1. X-ray crystallography (Lower resolution is the best one)

2. Organism: If you are working with humans include eg. Homosapiens if others select the species

3. Inhibitory ligand or cocrystal ligand should be preset in the selected PDB

4. If there are many PDB with the above criteria, check all shortlisted PDB with the cocrystal ligand and compare the IC50 or EC50 of the cocrystal ligands.

5. Finally select the lowest IC50-valued cocrystal ligand containing PDB for your study.

Best wishes for your work...

Thank you for your response.