Tibelius K H, Knowles R
J Bacteriol. 1984 Oct;160(1):103-6. doi: 10.1128/jb.160.1.103-106.1984.
Nitrite, NO, CO, and C2H2 inhibited O2-dependent H2 uptake (H3H oxidation) in denitrifying Azospirillum brasilense Sp7 grown anaerobically on N2O or NO3-. The apparent Ki values for inhibition of O2-dependent H2 uptake were 20 microM for NO2-, 0.4 microM for NO, 28 microM for CO, and 88 microM for C2H2. These inhibitors also affected methylene blue-dependent H2 uptake, presumably by acting directly on the hydrogenase. Nitrite and NO inhibited H2 uptake irreversibly, whereas inhibition due to CO was easily reversed by repeatedly evacuating and backfilling with N2. The C2H2 inhibition was not readily reversed, partly due to difficulty in removing the last traces of this gas from solution. The NO2- inhibition of malate-dependent respiration was readily reversed by repeatedly washing the cells, in contrast to the effect of NO2- on H2-dependent respiration. These results suggest that the low hydrogenase activities observed in NO3(-)-grown cultures of A. brasilense may be due to the irreversible inhibition of hydrogenase by NO2- and NO produced by NO3- reduction.
亚硝酸盐、一氧化氮、一氧化碳和乙炔抑制了在以一氧化二氮或硝酸根为厌氧生长底物的反硝化巴西固氮螺菌Sp7中依赖氧气的氢气摄取（H3H氧化）。抑制依赖氧气的氢气摄取的表观抑制常数（Ki）值，亚硝酸盐为20微摩尔，一氧化氮为0.4微摩尔，一氧化碳为28微摩尔，乙炔为88微摩尔。这些抑制剂也影响了依赖亚甲基蓝的氢气摄取，推测是通过直接作用于氢化酶。亚硝酸盐和一氧化氮不可逆地抑制氢气摄取，而一氧化碳引起的抑制通过反复抽空并用氮气回填很容易逆转。乙炔引起的抑制不容易逆转，部分原因是难以从溶液中去除这种气体的最后痕迹。与亚硝酸盐对依赖氢气的呼吸作用的影响相反，通过反复洗涤细胞，亚硝酸盐对依赖苹果酸的呼吸作用的抑制很容易逆转。这些结果表明，在巴西固氮螺菌以硝酸根生长的培养物中观察到的低氢化酶活性可能是由于硝酸根还原产生的亚硝酸盐和一氧化氮对氢化酶的不可逆抑制。
