Soybean root nodule acid phosphatase
Soybean root nodule acid phosphatase
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DOI：
10.1104/pp.114.2.597
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发表时间：
1997-06-01
期刊：
影响因子：
7.4
通讯作者：
Sarath, G
中科院分区：
文献类型：
--
作者：
Penheiter, AR;Duff, SMG;Sarath, G
酸性磷酸酶是普遍存在的酶，在体外表现出针对多种底物的活性，尽管对其细胞内功能知之甚少。在这项研究中，我们报告了大豆 (Glycine max L.) 根瘤中主要酸性磷酸酶的分离、表征和部分序列。磷酸酶主要纯化为亚基为 28 和 31 kD 的异二聚体；还观察到两个亚基的同二聚体并表现出磷酸酶活性。除了一般磷酸酶底物、磷酸对硝基苯酯之外，该酶的异二聚体形式还容易水解 5'-核苷酸、黄素单核苷酸和 O-磷酸-1-Tyr。观察到 ATP 或多磷酸盐的活性较低或可忽略不计。纯化的结节酸性磷酸酶受镁刺激，受钙和 EDTA 抑制，并受 cGMP 和 cAMP 竞争性抑制，表观 K-i 值分别为 7 和 12 μM。根瘤酸性磷酸酶的部分 N 末端和内部测序揭示了与大豆营养储存蛋白的同源性。在结节发育过程中，通过免疫印迹方法检测到酶活性增加了 17 倍，蛋白质水平也显着增加。这两个参数在年轻的结节中都很低，在成熟的功能性结节中达到峰值，表明这种酶对于有效的结节代谢很重要。
Acid phosphatases are ubiquitous enzymes that exhibit activity against a variety of substrates in vitro, although little is known about their intracellular function. In this study we report the isolation, characterization, and partial sequence of the major acid phosphatase from soybean (Glycine max L.) root nodules. The phosphatase was purified predominantly as a heterodimer with subunits of 28 and 31 kD; homodimers of both subunits were also observed and exhibited phosphatase activity. In addition to the general phosphatase substrate, p-nitrophenyl phosphate, the heterodimeric form of the enzyme readily hydrolyzed 5'-nucleotides, flavin mononucleotide, and O-phospho-1-Tyr. Low or negligible activity was observed with ATP or polyphosphate. Purified nodule acid phosphatase was stimulated by magnesium, inhibited by calcium and EDTA, and competitively inhibited by cGMP and cAMP with apparent K-i values of 7 and 12 mu M, respectively. Partial N-terminal and internal sequencing of the nodule acid phosphatase revealed homology to the soybean vegetative storage proteins. There was a 17-fold increase in enzyme activity and a noticeable increase in protein levels detected by immunoblotting methods during nodule development. Both of these parameters were low in young nodules and reached a peak in mature, functional nodules, suggesting that this enzyme is important for efficient nodule metabolism.