4U3H:
reference: Structural and dynamic properties that govern the stability of an engineered fibronectin type III domain., Porebski BT, Nickson AA, Hoke DE, Hunter MR, Zhu L, McGowan S, Webb GI, Buckle AM, Protein Eng Des Sel. 2015 Mar;28(3):67-78. doi: 10.1093/protein/gzv002. PMID: 25691761

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