Röckel D, Hernando J J, Vakalopoulou E, Post E, Oelze J
Arch Microbiol. 1983 Oct;136(1):74-8. doi: 10.1007/BF00415614.
Azotobacter vinelandii was grown in oxygen-controlled continuous cultures under conditions of dinitrogen fixation. Different oxygen concentrations were adjusted with air. Cell-free extracts were employed to study the oxygen dependency of the intracellular distribution and activity of the following enzymes: nitrogenase, glutamine synthetase and glutamate synthase. Nitrogenase was localized exclusively in the soluble fraction. Its activity increased steeply when the oxygen concentration employed in growing the organism decreased from about 30% close to 0% air saturation. Glutamine synthetase was identified exclusively as a soluble enzyme. The degree of adenylylation of the enzyme increased from about one to about four parallel to nitrogenase activity when the oxygen concentration in the culture was lowered. Glutamate synthase was detected in both a soluble and a membrane-bound form. The sum of specific activities of both forms stayed constant irrespective of changes in the oxygen concentration. However, with increasing oxygen concentration, the proportion of the membrane-bound form increased up to two-thirds of the total activity.
维涅兰德固氮菌在固氮条件下于氧气控制的连续培养物中生长。用空气调节不同的氧气浓度。采用无细胞提取物研究以下几种酶的细胞内分布和活性对氧气的依赖性：固氮酶、谷氨酰胺合成酶和谷氨酸合酶。固氮酶仅定位于可溶性部分。当用于培养该生物体的氧气浓度从约30%降至接近0%空气饱和度时，其活性急剧增加。谷氨酰胺合成酶仅被鉴定为一种可溶性酶。当培养物中的氧气浓度降低时，该酶的腺苷酸化程度从约1增加到约4，与固氮酶活性平行。谷氨酸合酶以可溶性和膜结合形式被检测到。两种形式的比活性总和保持恒定，与氧气浓度的变化无关。然而，随着氧气浓度的增加，膜结合形式的比例增加，直至总活性的三分之二。
