Interaction of Cm(iii) and Am(iii) with human serum transferrin studied by time-resolved laser fluorescence and EXAFS spectroscopy

Nicole Bauer,Daniel R. Fröhlich,Petra J. Panak

doi:10.1039/c3dt53371a

Nicole Bauer, Daniel R. Fröhlich + Show 1 more

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https://doi.org/10.1039/c3dt53371a

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Abstract

The complexation of Cm(III) with human serum transferrin was investigated in a pH range from 3.5 to 11.0 using time-resolved laser fluorescence spectroscopy (TRLFS). At pH ≥ 7.4 Cm(III) is incorporated at the Fe(III) binding site of transferrin whereas at lower pH a partially bound Cm(III) transferrin species is formed. At physiological temperature (310 K) at pH 7.4, about 70% of the partially bound and 30% of the incorporated Cm(III) transferrin species are present in solution. The Cm(III) results obtained by TRLFS are in very good agreement with Am(III) EXAFS results, confirming the incorporation of Am(III) at the Fe(III) binding site at pH 8.5.

Highlights

In the case of an accidental release of radionuclides to the environment, especially actinides cause a serious health risk upon incorporation into the body e.g. by wounds, ingestion or inhalation
The intensity of the Cm(III) EDTA emission band at λmax = 603.8 nm varies for different samples, indicating that transferrins from different suppliers contain varying amounts of EDTA (Fig. 2)
Since the Cm(III) concentration used for time-resolved laser fluorescence spectroscopy (TRLFS) measurements is quite low (c(Cm) = 1 × 10−7 M) and EDTA is a strong complexing agent, transferrin has to be purified before usage in complexation studies

Summary

Introduction

In the case of an accidental release of radionuclides to the environment, especially actinides cause a serious health risk upon incorporation into the body e.g. by wounds, ingestion or inhalation. In contrast to other metal ions, actinides have no essential function in the biochemistry of the human body.[1] Apart from chemical toxicity, their hazardousness depends on radiological toxicity. Availability and toxicity of the incorporated actinides in the body are mainly influenced by their concentration and speciation (chemical form and oxidation state).[2] Up to now, little is known about the chemical behavior and potential toxic effects of actinides in the human body. It is important to understand the mechanisms of relevant biochemical reactions with regard to the development of potential decontamination therapies.[3]

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