A.R.C. Research Group on Photosynthesis, Botany Department, University of Sheffield, S10 2TN, Sheffield, UK.
Planta. 1983 Jan;159(1):77-83. doi: 10.1007/BF00998817.
Intact chloroplasts prepared from summer-grown spinach plants supported (aspartate plus 2-oxoglutarate)-dependent O2 evolution but not (glutamine plus 2-oxoglutarate)-dependent O2 evolution. The former activity, which was sensitive to amino oxyacetate, was attributed to transaminase activity and reduction of the resulting oxalo-acetate to malate using H2O as eventual electron donor. A reconstituted chloroplast system which included chloroplast stroma, thylakoid membranes, ferredoxin and NADP(H) supported O2 evolution in the presence ofL-glutamine and 2-oxoglutarate at rates of 15-22 μmol mg(-1) chlorophyll h(-1) although lower rates were obtained with material from winter-grown plants. Activity was not observed in the absence of ferredoxin and omission of NADP(H) decreased activity by 40%. The reaction was associated with the production of 0.49 mol O2 mol(-1) 2-oxoglutarate consumed and up to 0.46 mol O2 mol(-1) glutamine supplied. The reaction, which was inhibited by azaserine but not by methionine sulphoximine or amino oxyacetate, was attributed to light-coupled glutamate synthase (EC 1.4.1.13) with H2O serving as eventual electron donor. Activity was not affected significantly byL-malate. The reconstituted system also supported O2 evolution in the presence of nitrite, oxaloacetate, (aspartate plus 2-oxoglutarate) and oxidised glutathione.
从夏季生长的菠菜植物中制备的完整叶绿体支持（天冬氨酸加 2-氧代戊二酸）依赖性 O2 演化，但不支持（谷氨酰胺加 2-氧代戊二酸）依赖性 O2 演化。前者的活性对氨基氧乙酸敏感，归因于转氨酶活性，并且使用 H2O 将由此产生的草酰乙酸还原为苹果酸，最终电子供体。包括叶绿体基质、类囊体膜、铁氧还蛋白和 NADP（H）的再组装叶绿体系统在存在 L-谷氨酰胺和 2-氧代戊二酸的情况下支持 O2 演化，速率为 15-22 μmol mg(-1)叶绿素 h(-1)，尽管来自冬季生长植物的材料获得的速率较低。在没有铁氧还蛋白的情况下没有观察到活性，并且省略 NADP（H）使活性降低了 40%。该反应与 0.49 mol O2 mol(-1)消耗的 2-氧代戊二酸和高达 0.46 mol O2 mol(-1)供应的谷氨酰胺的产生相关。该反应被天冬氨酸氨酸但不是甲硫氨酸亚砜或氨基氧乙酸抑制，归因于光偶联谷氨酸合酶（EC 1.4.1.13），H2O 作为最终电子供体。L-苹果酸对活性没有显著影响。再组装系统还支持在亚硝酸盐、草酰乙酸、（天冬氨酸加 2-氧代戊二酸）和氧化型谷胱甘肽存在下的 O2 演化。
