OXYGEN CONSUMPTION ASSOCIATED WITH FERRIC REDUCTASE ACTIVITY AND IRON UPTAKE BY IRON‐LIMITED CELLS OF CHLORELLA KESSLERI (CHLOROPHYCEAE)
OXYGEN CONSUMPTION ASSOCIATED WITH FERRIC REDUCTASE ACTIVITY AND IRON UPTAKE BY IRON‐LIMITED CELLS OF CHLORELLA KESSLERI (CHLOROPHYCEAE)
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与铁还原酶活性和铁限制小球藻（绿藻纲）细胞铁吸收相关的耗氧量
DOI：
10.1046/j.1529-8817.2001.037003393.x
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发表时间：
2001
影响因子：
2.9
通讯作者：
H. Weger
中科院分区：
文献类型：
--
作者：
Jocelyn K. Middlemiss;A. M. Anderson;Chad W. Stratilo;H. Weger
单细胞绿色小球藻（Chlorella kessleri Fott et Nováková）质膜铁还原酶活性在铁限制下提高了5倍。此外，铁限制细胞中的铁还原酶活性在光照下比在黑暗中高约50%。相比之下，铁限制细胞的铁摄取率不受光与暗处理的影响。铁的吸收率远低于铁还原率，平均约2%的黑暗铁还原率。铁还原与增加的O2消耗率在光明和黑暗中，在光的增加是在黑暗中的约1.5倍。过氧化氢酶的加入可使O2消耗的增加速率降低一半，表明H2O2是O2消耗的产物，并且增加的O2消耗是非呼吸性的。通过加入红菲咯啉二磺酸盐，一种强螯合剂的Fe 2+几乎完全取消了O2消耗的刺激。厌氧条件或外源性超氧化物歧化酶的存在下，既不影响铁还原，也不影响铁的吸收。我们认为，与铁还原酶活性相关的O2消耗导致从好氧氧化的Fe 2+，这是铁还原酶活性的产物形成超氧化物。在饱和浓度的Fe 3+螯合物，铁还原酶活性是远远大于铁的吸收率，导致快速氧化的Fe 2+和超氧化物的产生。因此，O2消耗不是铁同化过程的组成部分。
Plasma membrane ferric reductase activity was enhanced 5‐fold under iron limitation in the unicellular green alga Chlorella kessleri Fott et Nováková. Furthermore, ferric reductase activity in iron‐limited cells was approximately 50% higher in the light than in the dark. In contrast, iron uptake rates of iron‐limited cells were unaffected by light versus dark treatments. Rates of iron uptake were much lower than rates of ferric reduction, averaging approximately 2% of the dark ferric reduction rate. Ferric reduction was associated with an increased rate of O2 consumption in both light and dark, the increase in the light being approximately 1.5 times as large as in the dark. The increased rate of O2 consumption could be decreased by half by the addition of catalase, indicating that H2O2 is the product of the O2 consumption and that the increased O2 consumption is nonrespiratory. The stimulation of O2 consumption was almost completely abolished by the addition of bathophenanthroline disulfonate, a strong chelator of Fe2+. Anaerobic conditions or the presence of exogenous superoxide dismutase affected neither ferric reduction nor iron uptake. We suggest that the O2 consumption associated with ferric reductase activity resulted from superoxide formation from the aerobic oxidation of Fe2+, which is the product of ferric reductase activity. At saturating concentrations of Fe3+ chelates, ferric reductase activity is much greater than the iron uptake rate, leading to rapid oxidation of Fe2+ and superoxide generation. Therefore, O2 consumption is not an integral part of the iron assimilation process.
DOI：
10.1016/s0021-9258(18)54877-8
发表时间：
1991-10
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Bi Xu;N. Chasteen
通讯作者：
Bi Xu;N. Chasteen
DOI：
10.1073/pnas.96.19.10812
发表时间：
1999-09-14
影响因子：
11.1
作者：
Harris, ZL;Durley, AP;Gitlin, JD
通讯作者：
Gitlin, JD