2OXO:
reference: Crystallization and structure determination of the core-binding domain of bacteriophage lambda integrase., Kamadurai HB, Jain R, Foster MP, Acta Crystallogr Sect F Struct Biol Cryst Commun. 2008 Jun 1;64(Pt, 6):470-3. Epub 2008 May 17. PMID: 18540053

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