2O6M:
reference: Mutability of an HNH nuclease imidazole general base and exchange of a deprotonation mechanism., Eastberg JH, Eklund J, Monnat R Jr, Stoddard BL, Biochemistry. 2007 Jun 19;46(24):7215-25. Epub 2007 May 22. PMID: 17516660

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