Poly(gamma-glutamylcysteinyl)glycine: its role in cadmium resistance in plant cells.
Poly(gamma-glutamylcysteinyl)glycine: its role in cadmium resistance in plant cells.
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聚（γ-谷氨酰半胱氨酰）甘氨酸：其在植物细胞耐镉性中的作用。
DOI：
10.1073/pnas.84.19.6619
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发表时间：
1987
影响因子：
11.1
通讯作者：
Robinson,NJ
中科院分区：
文献类型：
--
作者：
Jackson,PJ;Unkefer,CJ;Doolen,JA;Watt,K;Robinson,NJ
可以根据在正常有毒浓度的某些痕量金属离子存在下生长的能力来选择被子植物。将镉和铜添加到抗镉曼陀罗细胞培养物中会导致富含硫的金属结合多肽的快速合成和积累。这些化合物的结构通过氨基酸分析、13C NMR 和位点特异性酶消化来确定。这些化合物是聚(γ-谷氨酰半胱氨酰)甘氨酸。在 Cd 抗性细胞中，超过 80% 的细胞 Cd 与双和三形式结合。金属结合多肽的最大积累量与细胞抵抗的有毒离子的浓度之间存在直接相关性。在金属离子存在的情况下，多肽形成多聚体聚集体，可以通过凝胶色谱法进行解析。 Cd 与高分子量和低分子量聚集体结合，而 Cu 优先与较高分子量形式结合。谷氨酰和相邻半胱氨酰残基之间存在γ-甲酰胺键表明这些多肽是生物合成途径的产物。聚（γ-谷氨酰半胱氨酰）甘氨酸与金属结合，在这方面，似乎是蛋白质金属硫蛋白的功能类似物。然而，在缺乏超最佳浓度的痕量金属离子的情况下，金属硫蛋白在动物和微生物中的功能与聚（γ-谷氨酰半胱氨酰）甘氨酸在植物中的功能可能不同。
Angiosperms can be selected for the ability to grow in the presence of normally toxic concentrations of certain trace metal ions. Addition of Cd and Cu to Cd-resistant Datura innoxia cell cultures results in the rapid synthesis and accumulation of sulfur-rich, metal-binding polypeptides. The structure of these compounds was determined using amino acid analysis, 13C NMR, and site-specific enzymic digestion. These compounds are poly(gamma-glutamylcysteinyl)glycines. Greater than 80% of the cellular Cd is bound to the bis and tris forms in Cd-resistant cells. There is a direct correlation between the maximum accumulation of the metal-binding polypeptides and the concentration of toxic ions to which the cells are resistant. In the presence of metal ions, the polypeptides form multimeric aggregates that can be resolved by gel chromatography. Cd binds to both the high and low molecular weight aggregates, whereas Cu preferentially binds to the higher molecular weight forms. The presence of gamma-carboxamide linkages between glutamyl and adjacent cysteinyl residues indicates that these polypeptides are products of biosynthetic pathways. Poly(gamma-glutamylcysteinyl)glycines bind metals and, in this respect, appear to be functional analogs of the protein metallothionein. However, in the absence of supraoptimal concentrations of trace metal ions, the functions of metallothionein in animals and microorganisms and poly(gamma-glutamylcysteinyl)glycines in plants may differ.