Spectroscopic studies on the interaction of europium(III) and curium(III) with components of the human mucosa

Lanthanide and actinide elements are exogenous metals, which have no essential role in normal biochemistry. Through different processes such as nuclear accidents, these heavy metals could be potentially released into the environment where they could be further incorporated eventually into the food chain and furthermore into the human gastrointestinal tract through oral ingestion. Because of their potential chemical- and radiotoxicity, it is important to understand their chemical and biological behavior in the human body. The digestive system is covered by a thick, viscoelastic mucosa membrane, which is a protective barrier to pathogens and toxic substances. The protective response in mucosa relies largely on the glycoprotein mucin. A previous spectroscopic screening with TRLFS (Time-Resolved Laser-Induced Fluorescence Spectroscopy) revealed mucin as a fundamental binding partner of Eu(III) as well as of Cm(III) in the human gastrointestinal tract. Based on these previous results, the present study focuses on this protein and its components to investigate its binding behavior with Eu(III) and Cm(III) as representatives of Ln(III) and An(III), respectively.