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作 者 ：朱素琴1,夏树林1,许 献1,卢 颖1,季本华1,梁建生2*

期 刊 ：西北植物学报 2013年 1期 页码：197~209

关键词：紫黄质循环；天线蛋白；类囊体膜脂；紫黄质脱环氧化酶；玉米黄质环氧化酶；

Keywords:violaxanthin cycle, antenna proteins, thylakoid membrane lipids, violaxanthine de-epoxidase (VDE), zeaxanthin epoxidase (ZEP),

摘 要 ：紫黄质循环是紫黄质(V)经过中间物单环氧玉米黄质(A)形成玉米黄质(Z)的可逆转换，是光合系统聚光复合体在低光下的聚光状态与高光下的能量耗散状态之间的转换开关。叶黄素中的玉米黄质可钝化（去激发）激发三线态叶绿素（³Chl^*）和激发单线态氧（¹O₂^*），紫黄质循环可直接或间接地通过非光化学淬灭（NPQ）耗散PSⅡ天线蛋白中的过量光能。天线蛋白被认为是依赖玉米黄质（Z）耗散过量光能的部位，天线蛋白通过结合紫黄质循环组分（V，A和Z）来调节紫黄质循环。 类囊体膜脂的性质和结构影响紫黄质循环组分（V，A和Z）间的转换，V的脱环氧化速率依赖于V在类囊体膜脂上侧向扩散的速率，紫黄质脱环氧化作用第一步（由V到A的转换）的速度常数是第二步（由A到Z的转换）速度常数的4～6倍。现有的结果表明，天线蛋白和类囊体膜脂是紫黄质循环最基本的调节器。该文对近年来国内外关于紫黄质循环的基本反应及其功能、紫黄质循环酶结构性质和辅因子以及天线蛋白和类囊体膜脂对紫黄质循环的调节作用及其机理等方面的研究进展进行了综述。

Abstract:The violaxanthin cycle (V-cycle),reversible conversion of violaxanthin (V) to zeaxanthin (Z) via the intermediate antheraxanthin (A),is a reversible switch of photosynthetic light-harvesting complexes between a light-harvesting state under low light and a dissipative state under high light.Xanthophylls such as zeaxanthin are known to play a crucial role in deactivating triplet chlorophyll (³Chl^*) and singlet oxygen (¹O₂^*).Violaxanthin cycle is further assumed to be involved either directly or indirectly in the non-photochemical quenching (NPQ) of excess light energy in the antenna of PSⅡ.Binding of xanthophylls by antenna proteins of both photosystems is essential to the regulation and function of the V-cycle.Because antenna proteins bind the substrates,V and Z,of the two Vx-cycle enzymes,VDE and ZEP,respectively,and antenna proteins are supposed to be the site for the Z-dependent dissipation of excess light energy.The lipid properties of the thylakoid membrane have a strong impact on xanthophyll conversion.The kinetics of violaxanthin de-epoxidation is likely to be limited by xanthophyll diffusion within the membrane.This assumption is supported by the fact that the first step of de-epoxidation (the V to A conversion) exhibits a 4～6 times higher rate constant than the second step (the A to Z conversion).The current knowledge supports the view that antenna proteins and thylakoid membrane lipids are essential modulators of violaxanthin cycle.Here a review is given on recent progress in the biochemical reaction and photoprotective functions of xanthophylls,structural properties of xanthophyll-cycle enzyme and cofactors,the regulation of xanthophyll cycle by antenna proteins and thylakoid membrane lipids.

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