玉米根细胞质膜硝酸还原酶的研究

以水双相分配分离法从玉米（Ｚｅａ ｍ ａｙｓＬ．）根细胞中提取的高纯度正面向外和内面向外的质膜囊泡为材料，鉴定出质膜上存在有硝酸还原酶（ＮＲ）。通过缺氮和加氮培养，证明质膜ＮＲ具有诱导性。外源电子供体实验表明，质膜ＮＲ除了能利用ＮＡＤＨ 作为电子供体外， 也能直接或间接利用ＮＡＤＰＨ 作为电子供体。通过Ｔｒｉｔｏｎ Ｘ－１００， 结合胰蛋白酶及其抑制剂实验证明了质膜ＮＲ是偏于膜外侧的跨膜蛋白，它对胰蛋白酶具有特异的敏感性。讨论了质膜ＮＲ的功能

STUDIES ON NITRATE REDUCTASE IN PLASMA MEMBRANE OF MAIZE ROOTS

Nitrate reductase (NR) activity was identified in the right side out and inside out of high purity plasma membrane (PM) vesicles in maize (Zea mays L.)roots which was obtained by aqueous two phase partitioning. The inducement property of the NR activity in PM could be confirmed through culturing the meterial with or without nitrate component. Analysis from experimentation with external electron donor indicated that the maize root NR in PM could utilize not only NADH but also NADPH directly or indirectly as its electron donor. Treatment with Triton X 100 combining with trypsin and inhibitor demonstrated that NR protein was a trans PM protein mainly facing the apoplastic side, being specially sensitive to trypsin. The possible function of the NR in PM is also discussed.