1GYY:
reference: The crystal structure of YdcE, a 4-oxalocrotonate tautomerase homologue from Escherichia coli, confirms the structural basis for oligomer diversity., Almrud JJ, Kern AD, Wang SC, Czerwinski RM, Johnson WH Jr, Murzin AG, Hackert ML, Whitman CP, Biochemistry 2002 Oct 8;41(40):12010-24. PMID: 12356301

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