1EM4:
reference: Stabilization of bound polycyclic aromatic hydrocarbons by a pi-cation interaction., Pellequer JL, Zhao B, Kao HI, Bell CW, Li K, Li QX, Karu AE, Roberts VA, J Mol Biol 2000 Sep 22;302(3):691-9. PMID: 10986127

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