Barkleit Astrid, Moll Henry, Bernhard Gert
Institute of Radiochemistry, Forschungszentrum Dresden-Rossendorf e.V., P.O box 510119, D-01314, Dresden, Germany.
Dalton Trans. 2008 Jun 7(21):2879-86. doi: 10.1039/b715669c. Epub 2008 Apr 18.
Bacteria have a great influence on the migration behaviour of heavy metals in the environment. Lipopolysaccharides form the main part of the outer membrane of Gram-negative bacteria. We investigated the interaction of the uranyl cation (UO2(2+)) with lipopolysaccharide (LPS) from Pseudomonas aeruginosa by using potentiometric titration and time-resolved laser-induced fluorescence spectroscopy (TRLFS) over a wide pH and concentration range. Generally, LPS consists of a high density of different functionalities for metal binding such as carboxyl, phosphoryl, amino and hydroxyl groups. The dissociation constants and corresponding site densities of these functional groups were determined using potentiometric titration. The combination of both methods, potentiometry and TRLFS, show that at an excess of LPS uranyl phosphoryl coordination dominates, whereas at a slight deficit on LPS compared to uranyl, carboxyl groups also become important for uranyl coordination. The stability constants of one uranyl carboxyl complex and three different uranyl phosphoryl complexes and the luminescence properties of the phosphoryl complexes are reported.
细菌对环境中重金属的迁移行为有很大影响。脂多糖构成革兰氏阴性菌外膜的主要部分。我们通过电位滴定法和时间分辨激光诱导荧光光谱法（TRLFS），在较宽的pH值和浓度范围内，研究了铀酰阳离子（UO2(2+)）与铜绿假单胞菌脂多糖（LPS）之间的相互作用。一般来说，LPS含有高密度的用于金属结合的不同官能团，如羧基、磷酰基、氨基和羟基。使用电位滴定法测定了这些官能团的解离常数和相应的位点密度。电位滴定法和TRLFS这两种方法的结合表明，在LPS过量时，铀酰磷酰配位占主导，而当LPS相对于铀酰略有不足时，羧基对铀酰配位也变得很重要。报告了一种铀酰羧基配合物和三种不同铀酰磷酰配合物的稳定常数以及磷酰配合物的发光特性。
