2FXV:
reference: The extraordinary specificity of xanthine phosphoribosyltransferase from Bacillus subtilis elucidated by reaction kinetics, ligand binding, and crystallography., Arent S, Kadziola A, Larsen S, Neuhard J, Jensen KF, Biochemistry. 2006 May 30;45(21):6615-27. PMID: 16716072

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