5KQ6:
reference: The Catalase Activity of Catalase-Peroxidases Is Modulated by Changes in the pKa of the Distal Histidine., Machuqueiro M, Victor B, Switala J, Villanueva J, Rovira C, Fita I, Loewen PC, Biochemistry. 2017 Apr 20. doi: 10.1021/acs.biochem.6b01276. PMID: 28409923

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