Acetylene brings about a progressive inactivation of ammonia mono-oxygenase, the ammonia-oxidizing enzyme in Nitrosomonas europaea. High NH4+ ion concentrations were protective. The inactivation followed first-order kinetics, with a rate constant of 1.5 min-1 at saturating concentrations of acetylene. If acetylene was added in the absence of O2, the cells remained active until O2 was re-introduced. A protective effect was also demonstrated with thiourea, a reversible non-competitive inhibitor of ammonia oxidation. Incubation of cells with [14C]acetylene was found to cause labelling of a single membrane polypeptide. This ran on dodecyl sulphate/polyacrylamide-gel electrophoresis with an Mr value of 28 000. It is concluded that acetylene is a suicide substrate for the mono-oxygenase. The labelling experiment provides the first identification of a constituent polypeptide of ammonia mono-oxygenase.
Research Article| May 01 1985
Suicidal inactivation and labelling of ammonia mono-oxygenase by acetylene
Biochem J (1985) 227 (3): 719–725.
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M R Hyman, P M Wood; Suicidal inactivation and labelling of ammonia mono-oxygenase by acetylene. Biochem J 1 May 1985; 227 (3): 719–725. doi: https://doi.org/10.1042/bj2270719
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