Interaction of the mechanism-based inactivator acetylene with ammonia monooxygenase of Nitrosomonas europaea

• DOI: 10.1099/mic.0.023721-0
• Publication Date: 2008-12-31T23:06:09Z
• Authors: Stefan Gilch; Manja Vogel; Matthias W. Lorenz; Ortwin Meyer; Ingo Schmidt
• Keywords: 0301 basic medicine; 0303 health sciences; Binding Sites; Acetylene; Molecular Sequence Data; Nitrosomonas europaea; Gene Expression Regulation, Bacterial; Ethylenes; Ketones; 03 medical and health sciences; Histidine; Amino Acid Sequence; Carbon Radioisotopes; Oxidoreductases; Peptides; Oxidation-Reduction

The ammonia monooxygenase (AMO) ofNitrosomonas europaeais a metalloenzyme that catalyses the oxidation of ammonia to hydroxylamine. We have identified histidine 191 of AmoA as the binding site for the oxidized mechanism-based inactivator acetylene. Binding of acetylene changed the molecular mass of His-191 from 155.15 to 197.2 Da (+42.05), providing evidence that acetylene was oxidized to ketene (CH2CO; 42.04 Da) which binds specifically to His-191. It must be assumed that His-191 is part of the acetylene-activating site in AMO or at least directly neighbours this site.