4MX1:
reference: Sulfur incorporation generally improves Ricin inhibition in pterin-appended glycine-phenylalanine dipeptide mimics., Wiget PA, Manzano LA, Pruet JM, Gao G, Saito R, Monzingo AF, Jasheway KR, Robertus JD, Anslyn EV, Bioorg Med Chem Lett. 2013 Dec 15;23(24):6799-804. PMID: 24432385

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