Copper isotope composition of hemocyanin
Marine Paquet1, Toshiyuki Fujii2, Frédéric Moynier1
1Université de Paris, Institut de Physique du Globe de Paris, CNRS, UMR 7154, 75005 Paris, France.
Summary
Copper stable isotopes are crucial for biological studies and disease biomarkers. Hemocyanin from mollusks and arthropods can serve as widely available biological standards for inter-laboratory copper isotope measurements.
Area of Science:
- Biogeochemistry
- Bioinorganic Chemistry
- Isotope Geochemistry
Background:
- Copper is a vital metal in biology, acting as a cofactor for redox enzymes.
- Stable copper isotopes trace biological transport and serve as biomarkers for diseases affecting copper homeostasis.
- Currently, a lack of standardized biological samples hinders inter-laboratory copper isotope analysis.
Purpose of the Study:
- To investigate the copper isotope composition of hemocyanin from various marine invertebrates.
- To assess the potential of hemocyanin as a biological standard for copper isotope measurements.
- To explore the theoretical basis of copper isotopic fractionation during hemocyanin formation.
Main Methods:
- Analysis of copper (Cu) isotope composition in hemocyanin from keyhole limpets, horseshoe crabs, and Chilean abalone.
- Utilizing ab initio calculations to understand theoretical constraints on isotopic fractionation.
- Comparing measured isotope compositions with seawater and literature values.
Main Results:
- Hemocyanin from Chilean abalone and horseshoe crabs showed copper isotope compositions indistinguishable from seawater, indicating quantitative copper absorption.
- Keyhole limpet hemocyanin exhibited enrichment in the lighter copper isotope, consistent with ab initio calculations and suggesting isotopic fractionation during copper incorporation.
- Theoretical calculations predicted enrichment of the lighter copper isotope in hemocyanin compared to seawater.
Conclusions:
- Widely available hemocyanin samples from marine invertebrates can serve as inter-laboratory standards.
- These standards will enhance the accuracy and reliability of copper isotope measurements in biological matrices.
- Establishing such standards is crucial for advancing the field of biological copper isotope applications.
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