Caris C, Baret P, Beguin C, Serratrice G, Pierre J L, Laulhère J P
Laboratoire d'Etudes Dynamiques et Structurales de la Sélectivité, Université J. Fourier, URA CNRS 0332, Grenoble, France.
Biochem J. 1995 Dec 15;312 ( Pt 3)(Pt 3):879-85. doi: 10.1042/bj3120879.
A synthetic siderophore, O-Trensox (L), has been designed and synthesized to improve iron nutrition of plants. The affinity for iron of this ligand [pFe(III) = 29.5 and pFe(II) = 17.9] is very high compared with EDTA. In spite of its high and specific affinity for iron, O-Trensox was found to be able to prevent, and to reverse, iron chlorosis in several plant species grown in axenic conditions. It also allows the iron nutrition and growth of Acer pseudoplatanus L. cell suspensions. The rate of iron metabolization was monitored by 59Fe radioiron. Ferritins, the iron storage proteins, are shown to be the first iron-labelled proteins during iron metabolization and to be able to further dispatch the metal. Using Fe(III)-Trensox, the rate of iron incorporation into ferritin was found to be higher than when using Fe-EDTA, but slower than with Fe-citrate, the natural iron carrier in xylem. During a plant cell culture, the extracellular concentrations of iron complex and free ligand were measured; changes in their relative amounts showed that the iron complex is dissociated extracellularly and that only iron is internalized. This suggests a high affinity for iron of a putative carrier on the plasmalemma. In contrast with Fe-citrate and Fe-EDTA complexes, Fe(III)-Trensox is not photoreducible. Its ability to induce radical damage as a Fenton reagent was tested using supercoiled DNA as target molecule. Unlike Fe-citrate and Fe-EDTA, Fe(II)-Trensox and Fe(III)-Trensox were proven to be harmless even during ascorbate-driven reduction, while Fe-EDTA and Fe-citrate generate heavy damage to DNA.
一种合成铁载体O-Trensox（L）已被设计并合成出来，用于改善植物的铁营养状况。与乙二胺四乙酸（EDTA）相比，这种配体对铁的亲和力非常高[pFe(III) = 29.5，pFe(II) = 17.9]。尽管O-Trensox对铁具有高亲和力和特异性，但研究发现它能够预防并逆转在无菌条件下生长的几种植物物种中的缺铁黄化现象。它还能促进假挪威槭（Acer pseudoplatanus L.）细胞悬浮液的铁营养和生长。通过59Fe放射性铁监测铁代谢速率。铁蛋白作为铁储存蛋白，在铁代谢过程中是首个被铁标记的蛋白质，并且能够进一步分配金属。使用Fe(III)-Trensox时，发现铁掺入铁蛋白的速率高于使用Fe-EDTA时，但比使用木质部中的天然铁载体柠檬酸铁时要慢。在植物细胞培养过程中，测量了铁络合物和游离配体的细胞外浓度；它们相对含量的变化表明，铁络合物在细胞外解离，只有铁被内化。这表明质膜上一种假定载体对铁具有高亲和力。与柠檬酸铁和Fe-EDTA络合物不同，Fe(III)-Trensox不能被光还原。以超螺旋DNA作为靶分子，测试了它作为芬顿试剂诱导自由基损伤的能力。与柠檬酸铁和Fe-EDTA不同，即使在抗坏血酸驱动的还原过程中，Fe(II)-Trensox和Fe(III)-Trensox也被证明是无害的，而Fe-EDTA和柠檬酸铁会对DNA造成严重损伤。
