4ER4:
reference: High resolution X-ray analyses of renin inhibitor-aspartic proteinase complexes., Foundling SI, Cooper J, Watson FE, Cleasby A, Pearl LH, Sibanda BL, Hemmings A, Wood SP, Blundell TL, Valler MJ, et al., Nature 1987 May 28-Jun 3;327(6120):349-52. PMID: 3295561

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