ROLE OF ASPARAGINE IN THE PHOTORESPIRATORY NITROGEN-METABOLISM OF PEA LEAVES
ROLE OF ASPARAGINE IN THE PHOTORESPIRATORY NITROGEN-METABOLISM OF PEA LEAVES
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DOI：
10.1104/pp.78.2.334
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发表时间：
1985-01-01
期刊：
影响因子：
7.4
通讯作者：
IRELAND, RJ
中科院分区：
文献类型：
--
作者：
TA, TC;JOY, KW;IRELAND, RJ
在豌豆叶中，进口天冬酰胺的大部分代谢是通过转氨作用进行的。这种活性以前被证明定位在过氧化体中，提示天冬酰胺和光呼吸氮代谢之间可能有联系。这是通过检查从天冬酰胺的氨基转移的15N，通过蒸腾流在完全展开的豌豆叶片中进行的。标记转移到天冬氨酸、谷氨酸、丙氨酸、甘氨酸、丝氨酸、氨和谷氨酰胺(氨基)。在低氧(1.8%)下或在α-羟基-2-吡啶甲烷磺酸(一种乙醇酸氧化酶的抑制剂，乙醛酸光呼吸形成的一个步骤)的存在下，标记转移到甘氨酸、丝氨酸、氨和谷氨酰胺的转移显著减少(60%-80%)。加入异烟酰肼(一种从甘氨酸生成丝氨酸的抑制剂)后，天冬酰胺氨基氮向丝氨酸、氨和谷氨酰胺的转移减少了70%，而甘氨酸的标记增加了4倍。结果表明，天冬酰胺参与了光呼吸，说明光呼吸氮代谢不是一个封闭的循环过程。
In pea leaves, much of the metabolism of imported asparagine is by transamination. This activity was previously shown to be localized in the peroxisomes, suggesting a possible connection between asparagine and photorespiratory nitrogen metabolism. This was investigated by examination of the transfer of15N from the amino group of asparagine, supplied via the transpiration stream, in fully expanded pea leaves. Label was transferred to aspartate, glutamate, alanine, glycine, serine, ammonia, and glutamine (amide group). Under low oxygen (1.8%), or in the presence of α-hydroxy-2-pyridine methanesulfonic acid (an inhibitor of glycolate oxidase, a step in the photorespiratory formation of glyoxylate), there was a substantial (60-80%) decrease in transfer of label to glycine, serine, ammonia, and glutamine. Addition of isonicotinyl hydrazide (an inhibitor of formation of serine from glycine) caused a 70% decrease in transfer of asparagine amino nitrogen to serine, ammonia, and glutamine, while a 4-fold increase in labeling of glycine was observed. The results demonstrate the involvement of asparagine in photorespiration, and show that photorespiratory nitrogen metabolism is not a closed cyclic process.