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Abstract：
The central ion Mg2+ is responsible for the differences between chlorophyll a and its free base in their reactivity toward metal ions and thus their resistance to oxidation. We present here the results of spectroscopic (electronic absorption and emission, circular dichroism, and electron paramagnetic resonance), spectroelectrochemical, and computational (based on density functional theory) investigations into the mechanism of pheophytin, a degradation that occurs in the presence of Cu ions and O2. The processes leading to the formation of the linear form of tetrapyrrole are very complex and involve the weakening of the methine bridge due to an electron withdrawal by Cu(II) and the activation of O2, which provides protection to the free ends of the opening macrocycle. These mechanistic insights are related to the naturally occurring damage to the photosynthetic apparatus of plants growing on metal-contaminated soils.
摘要：
中心离子Mg2负责叶绿素a及其游离碱对金属离子的反应性以及对氧化的抵抗力之间的差异。我们在这里介绍光谱的结果(电子吸收和发射，圆二色性,和电子顺磁共振)，光谱电化学，和计算（基于密度泛函理论）研究脱镁叶绿素的机理，在Cu离子和O2存在下发生的降解。导致形成线性形式的四吡咯的过程非常复杂，并且由于Cu（II）的电子抽出和O2的活化而导致次甲基桥的弱化，这为开放大环的自由端提供了保护。这些机械见解与在金属污染的土壤上生长的植物的光合装置的自然发生的损害有关。
