Keener W K, Russell S A, Arp D J
Laboratory for Nitrogen Fixation Research, Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley, Corvallis, OR 97331, USA.
Biochim Biophys Acta. 1998 Nov 10;1388(2):373-85. doi: 10.1016/s0167-4838(98)00188-5.
The kinetic mechanisms of seven inactivators of ammonia oxidation activity in cells of the nitrifying bacterium, Nitrosomonas europaea were investigated. The effects of the inactivators were specific for ammonia monooxygenase (AMO) which oxidizes ammonia to hydroxylamine. The aniline derivatives, 1,3-phenylenediamine and p-anisidine, were potent inactivators of AMO while other derivatives were ineffective as inactivators. Two cyclopropane derivatives, 1, 2-dimethylcyclopropane and cyclopropyl bromide, were inactivators while cyclopropane was not an inactivator. The mechanisms of three alkynes, 1-hexyne, 3-hexyne, and acetylene, were also examined. For all seven compounds, the inactivation of AMO was irreversible, time-dependent, first-order, and dependent on catalytic turnover. Saturation of the rate of inactivation was indicated for p-anisidine (kinact=2.85 min-1; KI=1.0 mM) and cyclopropyl bromide (kinact=4.4 min-1; KI=97 microM), but not for any of the remaining five inactivators, including acetylene. Ammonia slowed the rate of inactivation for acetylene and cyclopropyl bromide, but enhanced the rate of inactivation for the remaining inactivators. All seven compounds appear to be mechanism-based inactivators of AMO.
对硝化细菌欧洲亚硝化单胞菌（Nitrosomonas europaea）细胞中七种氨氧化活性失活剂的动力学机制进行了研究。这些失活剂的作用对将氨氧化为羟胺的氨单加氧酶（AMO）具有特异性。苯胺衍生物1,3 - 苯二胺和对甲氧基苯胺是AMO的有效失活剂，而其他衍生物作为失活剂则无效。两种环丙烷衍生物1,2 - 二甲基环丙烷和环丙基溴是失活剂，而环丙烷不是失活剂。还研究了三种炔烃1 - 己炔、3 - 己炔和乙炔的作用机制。对于所有七种化合物，AMO的失活都是不可逆的、时间依赖性的、一级的且依赖于催化周转。对甲氧基苯胺（kinact = 2.85 min⁻¹；KI = 1.0 mM）和环丙基溴（kinact = 4.4 min⁻¹；KI = 97 μM）表现出失活速率的饱和现象，但其余五种失活剂（包括乙炔）均未出现这种情况。氨减缓了乙炔和环丙基溴的失活速率，但提高了其余失活剂的失活速率。所有七种化合物似乎都是基于机制的AMO失活剂。
