3KCJ:
reference: Identification of the Elusive Hydronium Ion Exchanging Roles with a Proton in an Enzyme at Lower pH Values., Kovalevsky AY, Hanson BL, Mason SA, Yoshida T, Fisher SZ, Mustyakimov M, Forsyth VT, Blakeley MP, Keen DA, Langan P, Angew Chem Int Ed Engl. 2011 Aug 8;50(33):7520-3. doi:, 10.1002/anie.201101753. Epub 2011 May 23. PMID: 21604345

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