6JCV:
reference: Use of Cryo-EM To Uncover Structural Bases of pH Effect and Cofactor Bispecificity of Ketol-Acid Reductoisomerase., Chen CY, Chang YC, Lin BL, Lin KF, Huang CH, Hsieh DL, Ko TP, Tsai MD, J Am Chem Soc. 2019 Apr 2. doi: 10.1021/jacs.9b01354. PMID: 30921515

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