4KOA:
reference: The structure of substrate-free 1,5-anhydro-D-fructose reductase from Sinorhizobium meliloti 1021 reveals an open enzyme conformation., Schu M, Faust A, Stosik B, Kohring GW, Giffhorn F, Scheidig AJ, Acta Crystallogr Sect F Struct Biol Cryst Commun. 2013 Aug;69(Pt 8):844-9. doi:, 10.1107/S1744309113019490. Epub 2013 Jul 27. PMID: 23908025

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