6BGN:
reference: Inactivation of 4-Oxalocrotonate Tautomerase by 5-Halo-2-hydroxy-2,4-pentadienoates., Stack TMM, Li W, Johnson WH Jr., Zhang YJ, Whitman CP, Biochemistry. 2018 Feb 13;57(6):1012-1021. doi: 10.1021/acs.biochem.7b00899. Epub, 2018 Jan 24. PMID: 29303557

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