4DWW:
reference: Purification, crystallization and preliminary X-ray diffraction experiment of nattokinase from Bacillus subtilis natto., Yanagisawa Y, Chatake T, Chiba-Kamoshida K, Naito S, Ohsugi T, Sumi H, Yasuda I, Morimoto Y, Acta Crystallogr Sect F Struct Biol Cryst Commun. 2010 Dec 1;66(Pt 12):1670-3., Epub 2010 Nov 27. PMID: 21139221

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