4NO9:
reference: Systematic Comparison of Peptidic Proteasome Inhibitors Highlights the alpha-Ketoamide Electrophile as an Auspicious Reversible Lead Motif., Stein ML, Cui H, Beck P, Dubiella C, Voss C, Kruger A, Schmidt B, Groll M, Angew Chem Int Ed Engl. 2014 Feb 3;53(6):1679-83. doi: 10.1002/anie.201308984., Epub 2014 Jan 8. PMID: 24403024

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