2AX2:
reference: Production and X-ray crystallographic analysis of fully deuterated human carbonic anhydrase II., Budayova-Spano M, Fisher SZ, Dauvergne MT, Agbandje-McKenna M, Silverman DN, Myles DA, McKenna R, Acta Crystallograph Sect F Struct Biol Cryst Commun. 2006 Jan 1;62(Pt, 1):6-9. Epub 2005 Dec 16. PMID: 16511248

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