2YS6:
reference: Crystal structures of glycinamide ribonucleotide synthetase, PurD, from thermophilic eubacteria., Sampei G, Baba S, Kanagawa M, Yanai H, Ishii T, Kawai H, Fukai Y, Ebihara A, Nakagawa N, Kawai G, J Biochem. 2010 Oct;148(4):429-38. Epub 2010 Aug 16. PMID: 20716513

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