The soils contaminated by toxic metals are often remediated using EDTA and similar non-biodegradable chelators. Most chelators are in fact synthetic amino acid derivatives, whereas natural proteinogenic amino acids (PAAs) have not been systematically explored as remediation agents, despite their well-known metal chelating abilities and environmental benefits. Our study represents a comprehensive research exploring 16 structurally and functionally different PAAs as potential remediating agents, applied to 3 different heavy metal-contaminated samples. The study was mostly focused on extracting Cd, Cu, Ni, and Zn. The reaction parameters were screened and optimized. It was found that the efficiencies of extracting Cu, Ni, and Zn by Threonine, Aspartic acid and Histidine were comparable to those by EDTA, whereas non-polar side chain-containing PAAs demonstrated consistently lower PTM extraction rates compared to other PAAs. The sulfur-containing Cysteine appeared to be efficient to extract Cd (to some extent), Ni and Zn, but not Cu, due to chemical reasons. The structure-functional correlations were identified, described, and found to be independent on the specific samples. Possible molecular mechanisms of metal extraction from soils by PAAs are discussed. In contrast to EDTA, the soil-essential elements are almost not extracted by PAAs. This important feature of the PAAs, along with their availability, observed selectivity, competitive efficiency, non-toxicity and even fertilizing properties, make them particularly soil-friendly, and thus, potentially applicable chelators in certain remediation processes.

中文翻译：

---

天然氨基酸可作为土壤修复的潜在螯合剂。

通常使用EDTA和类似的不可生物降解的螯合剂对有毒金属污染的土壤进行修复。实际上，大多数螯合剂都是合成氨基酸衍生物，而天然蛋白原氨基酸（PAA）尽管具有众所周知的金属螯合能力和环境效益，但尚未得到系统地研究作为修复剂。我们的研究代表了一项全面的研究，探索了16种在结构和功能上不同的PAA作为潜在的修复剂，并将其应用于3种不同的重金属污染样品。该研究主要集中在提取Cd，Cu，Ni和Zn。筛选和优化反应参数。发现苏氨酸，天门冬氨酸和组氨酸提取铜，镍和锌的效率与EDTA相当。与其他PAA相比，非极性侧链PAA的PTM提取率始终较低。由于化学原因，含硫半胱氨酸似乎可以有效地萃取Cd（在某种程度上），Ni和Zn，但不能萃取Cu。鉴定，描述并发现结构-功能相关性与特定样品无关。讨论了通过PAA从土壤中提取金属的可能分子机理。与EDTA相比，PAA几乎不提取土壤必需元素。PAA的这一重要特征，以及其可用性，观察到的选择性，竞争效率，无毒，甚至施肥特性，使其对土壤特别友好，因此在某些修复过程中可能适用。