Hyman M R, Wood P M
Biochem J. 1983 Apr 15;212(1):31-7. doi: 10.1042/bj2120031.
Methane inhibited NH4+ utilization by Nitrosomonas europaea with a Ki of 2mM. O2 consumption was not inhibited. In the absence of NH4+, or with hydrazine as reductant, methane caused nearly a doubling in the rate of O2 uptake. The stimulation was abolished by allylthiourea, a sensitive inhibitor of the oxidation of NH4+. Analysis revealed that methanol was being formed in these experiments, with yields approaching 1 mol of methanol per mol of O2 consumed under certain conditions. When cells were incubated with NH4+ under an atmosphere of 50% methane, 50 microM-methanol was generated in 1 h. It is concluded that methane is an alternative substrate for the NH3-oxidizing enzyme (ammonia mono-oxygenase),m albeit with a much lower affinity than for methane mono-oxygenase of methanotrophs.
甲烷抑制欧洲亚硝化单胞菌利用NH₄⁺，其抑制常数（Ki）为2mM。氧气消耗未受抑制。在没有NH₄⁺的情况下，或者以肼作为还原剂时，甲烷使氧气摄取速率几乎翻倍。烯丙基硫脲（一种对NH₄⁺氧化敏感的抑制剂）消除了这种刺激作用。分析表明，在这些实验中会形成甲醇，在某些条件下，每消耗1摩尔氧气，甲醇产量接近1摩尔。当细胞在50%甲烷气氛下与NH₄⁺一起孵育时，1小时内会产生50微摩尔甲醇。得出的结论是，甲烷是氨氧化酶（氨单加氧酶）的替代底物，尽管其亲和力比甲烷营养菌的甲烷单加氧酶低得多。
