2KAI:
reference: Refined 2.5 A X-ray crystal structure of the complex formed by porcine kallikrein A and the bovine pancreatic trypsin inhibitor. Crystallization, Patterson search, structure determination, refinement, structure and comparison with its components and with the bovine trypsin-pancreatic trypsin inhibitor complex., Chen Z, Bode W, J Mol Biol 1983 Feb 25;164(2):283-311. PMID: 6188842

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