4WBC:
reference: Cryocrystallography of a Kunitz-type serine protease inhibitor: the 90 K structure of winged bean chymotrypsin inhibitor (WCI) at 2.13 A resolution., Ravichandran S, Sen U, Chakrabarti C, Dattagupta JK, Acta Crystallogr D Biol Crystallogr 1999 Nov;55(11):1814-21. PMID: 10531477

This OCA Structure page
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