Department of Botany, Duke University, Durham, North Carolina 27706.
Plant Physiol. 1991 Jun;96(2):355-62. doi: 10.1104/pp.96.2.355.
Nitrogen partitioning among proteins in chloroplasts and mitochondria was examined in pea (Pisum sativum L.) and wheat (Triticum aestivum L.) grown hydroponically with different nitrogen concentrations. In pea leaves, chloroplast nitrogen accounted for 75 to 80% of total leaf nitrogen. We routinely found that 8% of total ribulose-1,5-bisphosphate carboxylase/oxygenase adhered to thylakoids during preparation and could be removed with Triton X-100. With this precaution, the ratio of stroma nitrogen increased from 53 to 61% of total leaf nitrogen in response to the nitrogen supply, but thylakoid nitrogen remained almost constant around 20% of total. The changes in the activities of the stromal enzymes and electron transport in response to the nitrogen supply reflected the nitrogen partitioning into stroma and thylakoids. On the other hand, nitrogen partitioning into mitochondria was appreciably smaller than that in chloroplasts, and the ratio of nitrogen allocated to mitochondria decreased with increasing leaf-nitrogen content, ranging from 7 to 4% of total leaf nitrogen. The ratio of mitochondrial respiratory enzyme activities to leaf-nitrogen content also decreased with increasing leaf-nitrogen content. These differences in nitrogen partitioning between chloroplasts and mitochondria were reflected in differences in the rates of photosynthesis and dark respiration in wheat leaves measured with an open gas-exchange system. The response of photosynthesis to nitrogen supply was much greater than that of dark respiration, and the CO(2) compensation point decreased with increasing leaf-nitrogen content.
我们研究了水培条件下不同氮浓度对豌豆（Pisum sativum L.）和小麦（Triticum aestivum L.）叶片和线粒体中蛋白氮分配的影响。在豌豆叶片中，叶绿体氮占叶片总氮的 75%到 80%。我们通常发现，在制备过程中有 8%的核酮糖-1,5-二磷酸羧化酶/加氧酶与类囊体结合，可以用 Triton X-100 去除。采取这一预防措施后，基质氮的比例从总叶片氮的 53%增加到 61%，以响应氮的供应，但类囊体氮几乎保持在总氮的 20%左右不变。基质酶和电子传递活性对氮供应的响应变化反映了氮在基质和类囊体中的分配。另一方面，氮在向线粒体中的分配明显小于在叶绿体中的分配，并且分配给线粒体的氮的比例随着叶片氮含量的增加而降低，范围从总叶片氮的 7%到 4%。线粒体呼吸酶活性与叶片氮含量的比值也随着叶片氮含量的增加而降低。叶绿体和线粒体之间氮分配的这些差异反映在通过开放式气体交换系统测量的小麦叶片光合作用和暗呼吸速率的差异上。氮供应对光合作用的响应远大于对暗呼吸的响应，并且随着叶片氮含量的增加，CO2 补偿点降低。
