4HDB:
reference: Novel P2 tris-tetrahydrofuran group in antiviral compound 1 (GRL-0519) fills the S2 binding pocket of selected mutants of HIV-1 protease., Zhang H, Wang YF, Shen CH, Agniswamy J, Rao KV, Xu CX, Ghosh AK, Harrison RW, Weber IT, J Med Chem. 2013 Feb 14;56(3):1074-83. doi: 10.1021/jm301519z. Epub 2013 Jan 23. PMID: 23298236

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