4OEX:
reference: Thermodynamic and structural characterization of halogen bonding in protein-ligand interactions: a case study of PDE5 and its inhibitors., Ren J, He Y, Chen W, Chen T, Wang G, Wang Z, Xu Z, Luo X, Zhu W, Jiang H, Shen J, Xu Y, J Med Chem. 2014 Apr 24;57(8):3588-93. doi: 10.1021/jm5002315. Epub 2014 Apr 15. PMID: 24702184

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