4D56:
reference: Structural Elucidation of the Bispecificity of A Domains as a Basis for Activating Non-natural Amino Acids., Kaljunen H, Schiefelbein SH, Stummer D, Kozak S, Meijers R, Christiansen G, Rentmeister A, Angew Chem Int Ed Engl. 2015 Jun 11. doi: 10.1002/anie.201503275. PMID: 26096082

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