4KN8:
reference: Crystal structure of thermostable p-nitrophenylphosphatase from Bacillus Stearothermophilus (Bs-TpNPPase)., Guo Z, Wang F, Shen T, Huang J, Wang Y, Ji C, Protein Pept Lett. 2014 May;21(5):483-9. PMID: 24256105

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