2ABB:
reference: Proton transfer in the oxidative half-reaction of pentaerythritol tetranitrate reductase. Structure of the reduced enzyme-progesterone complex and the roles of residues Tyr186, His181, His184., Khan H, Barna T, Bruce NC, Munro AW, Leys D, Scrutton NS, FEBS J 2005 Sep;272(18):4660-71. PMID: 16156787

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