3ZGC:
reference: Crystal-contact engineering to obtain a crystal form of the Kelch domain of human Keap1 suitable for ligand-soaking experiments., Horer S, Reinert D, Ostmann K, Hoevels Y, Nar H, Acta Crystallogr Sect F Struct Biol Cryst Commun. 2013 Jun;69(Pt 6):592-6. doi:, 10.1107/S174430911301124X. Epub 2013 May 23. PMID: 23722832

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