烟草叶片中甘氨酸氧化与硝酸还原的关系

THE RELATIONSHIP BETWEEN GLYCINE OXIDATION AND NITRATE REDUCTION IN TOBACCO LEAVES

本试验用烟草(Nicotiana tabacum L.)叶圆片和由其线粒体和硝酸还原酶组成的重组系统对甘氨酸氧化与硝酸还原的关系进行了研究。结果表明,甘氨酸真空渗入叶圆片或加入重组系统中都能促进硫酸还原。甘氨酸对硝酸还原的促进作用明显受取样前预照光处理及呼吸链活性的影响。硝酸还原的进行使线粒体依赖甘氨酸的耗氧率降低。本文认为,光下 C_3 植物叶片中的甘氨酸氧化脱羧能为硝酸还原提供还原剂。

The relationship between glycine oxidation and nitrate reduction was studied using to- bacco(Nicotiana tabacum L.)leaf disks and reconstituted system of isolated mitochondria and NR(Nitrate reductase).It was found that gly ine,either vacuum-infiltrated in to leaf disks or added to the reconstituted system,could increase the rate of nitrate reduction.The stimu- lating effect of glycine on nitrate reduction was greatly influenced by preillumination treat- ment of tobacco leaves,and also by the activity of respiratory chain.The rate of glycine- dependent O_2 consumption by mitochondria was lowered when KNO_3 and NR were added to the system.It was also found that the activity of glycine decarboxylase increased with incre- ase in nitrate concentrations in the sandculture medium.It was concluded that oxidative de- carboxylation of glycine in mitochondria of leaf cells of C_3 plants could provide NADH for nitrate reduction in cytoplasm in the light,and nitrate reduction and glycine oxidation were influenced by each other.