潜在的硝酸还原酶活性与玉米根的质膜有关。

Latent nitrate reductase activity is associated with the plasma membrane of corn roots.

机构信息

Plant Growth Laboratory, University of California, 95616, Davis, CA, USA.

出版信息

Planta. 1989 Apr;177(4):470-5. doi: 10.1007/BF00392614.

Abstract

Latent nitrate reductase activity (NRA) was detected in corn (Zea mays L., Golden Jubilee) root microsome fractions. Microsome-associated NRA was stimulated up to 20-fold by Triton X-100 (octylphenoxy polyethoxyethanol) whereas soluble NRA was only increased up to 1.2-fold. Microsome-associated NRA represented up to 19% of the total root NRA. Analysis of microsomal fractions by aqueous two-phase partitioning showed that the membrane-associated NRA was localized in the second upper phase (U2). Analysis with marker enzymes indicated that the U2 fraction was plasma membrane (PM). The PM-associated NRA was not removed by washing vesicles with up to 1.0 M NACl but was solubilized from the PM with 0.05% Triton X-100. In contrast, vanadate-sensitive ATPase activity was not solubilized from the PM by treatment with 0.1% Triton X-100. The results show that a protein capable of reducing nitrate is embedded in the hydrophobic region of the PM of corn roots.

摘要

玉米（Zea mays L.，Golden Jubilee）根微粒体部分中检测到潜伏的硝酸还原酶活性（NRA）。Triton X-100（辛基酚聚氧乙烯醚）可将微粒体相关的 NRA 刺激高达 20 倍，而可溶性 NRA 仅增加至 1.2 倍。微粒体相关的 NRA 占总根 NRA 的高达 19%。通过水相两相分配分析微粒体部分表明，膜相关的 NRA 位于第二上层（U2）。用标记酶进行分析表明，U2 部分是质膜（PM）。用高达 1.0 M NACl 洗涤囊泡不能去除 PM 相关的 NRA，但用 0.05% Triton X-100 可从 PM 中溶解。相比之下，用 0.1% Triton X-100 处理不会从 PM 中溶解钒酸盐敏感的 ATP 酶活性。结果表明，一种能够还原硝酸盐的蛋白质嵌入玉米根质膜的疏水区。