Murry M A, Fontaine M S, Tjepkema J D
Arch Microbiol. 1984 Oct;139(2-3):162-6. doi: 10.1007/BF00401993.
O2 protection of nitrogenase in a cultured Frankia isolate from Alnus rubra (HFPArI3) was studied in vivo. Evidence for a passive gas diffusion barrier in the vesicles was obtained by kinetic analysis of in vivo O2 uptake and acetylene reduction rates in response to substrate concentration. O2 of NH4+-grown cells showed an apparent KmO2 of approximately 1 microM O2. In N2-fixing cultures a second Km O2 of about 215 microM O2 was observed. Thus, respiration remained unsaturated by O2 at air-saturation levels. In vivo, the apparent Km for acetylene was more than 10-fold greater than reported in vitro values. These data were interpreted as evidence for a gas diffusion barrier in the vesicles but not vegetative filaments of Frankia sp. HFPArI3.
在体内研究了从红桤木分离的培养弗氏放线菌（HFPArI3）中固氮酶的氧气保护作用。通过对体内氧气摄取和乙炔还原速率对底物浓度响应的动力学分析，获得了泡囊中存在被动气体扩散屏障的证据。以NH4 +生长的细胞的氧气显示出约1 microM O2的表观KmO2。在固氮培养物中，观察到约215 microM O2的第二个Km O2。因此，在空气饱和水平下，呼吸作用未被氧气饱和。在体内，乙炔的表观Km比体外报道的值大10倍以上。这些数据被解释为弗氏放线菌HFPArI3泡囊中存在气体扩散屏障的证据，但营养菌丝中不存在。
