Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii: experiments using iron-limited chemostats
Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii: experiments using iron-limited chemostats
复制标题
绿藻莱茵衣藻中的铁和铜还原酶活性：使用限铁恒化器的实验
作者：
H. Weger
抽象的。将莱茵衣藻(Chlamydomonas Reinhardtii Dangeard)绿藻细胞培养在铁限制的恒化器中，生长速度为0.15~1.5 d−1。与使用1：1的螯合剂：FeCl3生长相比，使用过量的螯合剂[乙二胺二(邻羟基苯乙酸)]相对于FeCl3(80：1)可以获得更高的细胞密度和培养的叶绿素水平。随着铁限制生长速率的增加，莱茵梭菌细胞减少了胞外螯合铁，铁螯合还原酶的活性增加。然而，铁充足的细胞表现出较低的铁螯合还原酶活性，与严重铁限制的细胞相似。铁限制细胞能够以相似的速率还原代表大范围稳定常数的多种铁络合物，这表明铁络合物的稳定常数不是铁还原活性的重要决定因素。铜还原酶活力也随着铁限制生长速率的增加而增加，与铁(III)相比，铜(II)优先还原。这些结果表明，这两种还原酶活性可能代表相同的质膜酶。铜还原速率是游离[Cu2+]的函数，而不是总[Cu2+]的函数，这表明自由Cu2+是Cu2+还原酶活性的实际底物。
Abstract. Cells of the green alga Chlamydomonas reinhardtii Dangeard were grown in Fe-limited chemostat culture over a range of growth rates (0.15–1.5 d−1). Greater cell densities and culture chlorophyll levels were achieved using an excess of chelator [ethylenediamine di-(o-hydroxyphenylacetic acid)] relative to FeCl3 (80:1), compared to growth using a 1:1 chelator:FeCl3 ratio. The C. reinhardtii cells reduced extracellular ferric chelates, and ferric chelate reductase activity increased with increasing Fe-limited growth rates. However Fe-sufficient cells exhibited a low rate of ferric chelate reductase activity, similar to severely Fe-limited cells. Iron-limited cells were capable of reducing a wide variety of ferric chelates, representing a wide range of stability constants, at similar rates, suggesting that the stability constants of ferric complexes are not important determinants of ferric reducing activity. Cupric reductase activity also increased with increasing Fe-limited growth rates, and Cu(II) was preferentially reduced compared to Fe(III). These results suggest that both reductase activities may represent the same plasma-membrane enzyme. The rate of cupric reduction was a function of the free [Cu2+], not the total [Cu(II)], suggesting that free Cu2+ is the actual substrate for cupric reductase activity.
在大鼠肝质膜存在的情况下从二铁转铁蛋白释放铁：没有质膜二铁转铁蛋白还原酶的证据。
DOI：
10.1016/0167-4889(90)90053-g
发表时间：
1990
期刊：
Biochimica et biophysica acta
影响因子：
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作者：
Thorstensen,K;Aisen,P
通讯作者：
Aisen,P