2ZFE:
reference: Effect of Xenon Binding to a Hydrophobic Cavity on the Proton Pumping Cycle in Bacteriorhodopsin., Hayakawa N, Kasahara T, Hasegawa D, Yoshimura K, Murakami M, Kouyama T, J Mol Biol. 2008 Oct 9. PMID: 18930734

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