Iodine uptake in Laminariales involves extracellular, haloperoxidase-mediated oxidation of iodide
Iodine uptake in Laminariales involves extracellular, haloperoxidase-mediated oxidation of iodide
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DOI：
10.1007/s004250050469
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发表时间：
1998-12-01
期刊：
影响因子：
4.3
通讯作者：
Kloareg, B
中科院分区：
文献类型：
--
作者：
Küpper, FC;Schweigert, N;Kloareg, B
海带的孢子体（L.）Lamour。测定了它们的累积碘含量，其范围从成年植株干重的0.4%到幼芽植株的4.7%。saccharina （L.）的孢子体组织Lamour。L. digitata根据Michaelis-Menten动力学吸收碘。过氧化氢和各种已知干扰氧化代谢的物质被证明抑制或增强碘的摄取，证实了藻外氧化在海带碘的摄取中起关键作用。与此一致的是，在双氧水的存在下孵育会触发糖精酵母原生质体对碘的吸收。同样，添加卤素过氧化物酶可以增强L. digitata配子体对碘的吸收，表明该酶催化过氧化氢氧化碘，在碘吸收中起关键作用。氧化应激导致细胞内碘的明显外排。在流入和流出实验中，有相当比例的示踪剂（10-30%）没有被考虑在内，这表明碘的挥发。讨论了海带积累碘的机理和可能的功能。
Sporophytes of Laminaria digitata (L.) Lamour. were assayed for their content of accumulated iodine, which ranged from 0.4% of dry weight in adult plants up to 4.7% for young plantlets. Sporophyte tissue from Laminaria saccharina (L.) Lamour. and L. digitata took up iodide according to Michaelis-Menten kinetics. Hydrogen peroxide and various substances known to interfere with oxidative metabolism were shown to either inhibit or enhance the uptake of iodide, confirming that apoplastic oxidations play a key role in iodide uptake in Laminaria. Consistently, iodide uptake was triggered in L. saccharina protoplasts by incubation in the presence of hydrogen peroxide. Similarly, the uptake of iodide was enhanced in L. digitata gametophytes by addition of haloperoxidase, suggesting that this enzyme catalyses the oxidation of iodide by hydrogen peroxide and plays a key role in iodine uptake. Oxidative stress resulted in a marked efflux of the intracellular iodine. In both influx and efflux experiments, a marked proportion (10-30%) of the tracer was not accounted for, indicating volatilisation of iodine. The mechanism and possible functions of the accumulation of iodine by kelps are discussed.