Ascorbate synthesis and ascorbate peroxidase activity during the early stage of wheat germination
Ascorbate synthesis and ascorbate peroxidase activity during the early stage of wheat germination
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DOI：
10.1034/j.1399-3054.1997.1000415.x
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发表时间：
1997-08-01
影响因子：
6.4
通讯作者：
Arrigoni, O
中科院分区：
文献类型：
--
作者：
DeGara, L;dePinto, MC;Arrigoni, O
以小麦（Triticum durum L.）CV. Norba）完全不含抗坏血酸盐（ASC），但含有少量的脱氢抗坏血酸盐（DHA）。ASC的从头生物合成在发芽8-10小时后在小麦胚中开始，但在ASC生物合成途径完全恢复之前，胚可以通过减少储存的DHA来为自己提供ASC。三种不同的蛋白质具有减少DHA的能力，存在于胚胎在萌发的早期阶段。然而，当从糖开始的ASC生物合成完全恢复时，DHA还原能力大大下降，只有一种DHA还原蛋白保持活性。存在的三种蛋白质具有DHA-还原能力和他们的行为在germination.Dry胚胎也缺乏ASC过氧化物酶（EC 1.11.1.11），这种过氧化氢清除酶出现后，同样的滞后ASC和增加在萌发过程中平行的上升ASC。当ASC生物合成被实验诱导时，ASC过氧化物酶也较早出现;此外，在萌发过程中逐渐出现的三种ASC过氧化物酶同工酶对ASC的亲和力取决于胚中可用的ASC：当ASC含量非常低时，第一种同工酶中的亲和力最高，当ASC含量高出10-11倍时，最后表达的同工酶中的亲和力最低。
Embryos from dry caryopses of wheat (Triticum durum L. cv. Norba) are completely devoid of ascorbate (ASC) but contain a low amount of dehydroascorbate (DHA). The de novo biosynthesis of ASC starts in the wheat embryos after 8-10 h of germination but before the ASC biosynthetic pathway is completely restored the embryos can provide themselves with ASC by the reduction of the stored DHA. Three different proteins having DHA-reducing capability are present in the embryos during the early stages of germination. However, when the de novo ASC biosynthesis from sugar is completely restored, the DHA reduction capability largely drops and only one DHA-reducing protein remains active. The presence of three proteins having DHA-reducing capability and their behaviour during germination is discussed.Dry embryos are also devoid of ASC peroxidase (EC 1.11.1.11); this hydrogen peroxide scavenger enzyme appears after the same lag as ASC and increases during germination in parallel with the rise in ASC. When ASC biosynthesis is experimentally induced, the ASC peroxidase also appears earlier; moreover the affinities for ASC of the three ASC peroxidase isoenzymes that progressively appear during germination depend on the ASC available in the embryos: highest in the first isoenzyme, that appears when the ASC content is very low, lowest in the isoenzyme that is expressed last, when the ASC content is 10-11 times higher.