1GH4:
reference: Observation of additional calcium ion in the crystal structure of the triple mutant K56,120,121M of bovine pancreatic phospholipase A2., Rajakannan V, Yogavel M, Poi MJ, Jeyaprakash AA, Jeyakanthan J, Velmurugan D, Tsai MD, Sekar K, J Mol Biol 2002 Dec 6;324(4):755-62. PMID: 12460575

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