Bennett K J, Silvester W B, Brown J M
Arch Microbiol. 1975 Sep 30;105(1):61-6. doi: 10.1007/BF00447114.
Exogenous pyruvate added to cultures of the blue-green alga, Anabaena cylindrica stimulated nitrogenase activity (measured by acetylene reduction) only in the dark under low pO2 (0.05 atmospheres). Under aerobic conditions or in the light, stimulation was absent and replaced by an inhibition of activity above 5 mM added pyruvate. The curve of nitrogenase activity versus oxygen concentration had a similar maximal value of ethylene production with, or without added pyruvate, but in the presence of pyruvate this maximum occurred at 0.05 atmospheres O2, whilst in the absence of pyruvate the maximum occurred at 0.10 atmospheres O2. Malate, citrate, alpha-ketoglutarate, glucose and fructose were tested also, but none gave a similar effect to pyruvate. Addition of 14C-pyruvate and autoradiography indicated that exogenous pyruvate is metabolized through the interrupted Krebs cycle. These results are explained in terms of the activity of pyruvate: ferredoxin oxidoreductase and the ATP-induced oxygen sensitivity of nitrogenase.
添加到蓝藻圆柱鱼腥藻培养物中的外源丙酮酸，仅在低氧分压（0.05个大气压）的黑暗条件下刺激固氮酶活性（通过乙炔还原法测定）。在有氧条件下或光照条件下，不存在刺激作用，且当添加的丙酮酸浓度高于5 mM时，固氮酶活性受到抑制。无论是否添加丙酮酸，固氮酶活性与氧气浓度的曲线都有相似的乙烯产量最大值，但在有丙酮酸存在的情况下，该最大值出现在0.05个大气压的氧气浓度下，而在没有丙酮酸的情况下，最大值出现在0.10个大气压的氧气浓度下。还测试了苹果酸、柠檬酸、α-酮戊二酸、葡萄糖和果糖，但它们都没有产生与丙酮酸类似的效果。添加14C-丙酮酸并进行放射自显影表明，外源丙酮酸通过中断的三羧酸循环进行代谢。这些结果可以用丙酮酸：铁氧还蛋白氧化还原酶的活性以及固氮酶对ATP诱导的氧敏感性来解释。
