4HA2:
reference: A conserved tryptophan (W91) at the barrel-lid junction modulates the packing and stability of Kunitz (STI) family of inhibitors., Majumder S, Khamrui S, Banerjee R, Bhowmik P, Sen U, Biochim Biophys Acta. 2015 Jan;1854(1):55-64. doi: 10.1016/j.bbapap.2014.10.021. , Epub 2014 Oct 31. PMID: 25448016

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