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Summary
Citrate is a key plasma binder for aluminum (Al3+) and iron (Fe3+). Understanding citrate
Area of Science:
- Biochemistry
- Toxicology
- Analytical Chemistry
Background:
- Citrate is a prevalent small molecule in blood plasma (approx. 0.1 mM).
- Citrate is a likely plasma binder for both aluminum (Al3+) and iron (Fe3+).
Purpose of the Study:
- To assess published stability constants for citrate binding to Al3+ and Fe3+.
- To evaluate the implications of citrate-metal interactions in biological systems.
Main Methods:
- Literature review of published stability constants for citrate-metal complexes.
- Analysis of metal-citrate complex formation across a pH range (2-5).
Main Results:
- Al3+ forms a neutral complex with citrate between pH 2 and 5, potentially facilitating gastrointestinal absorption.
- A competing 2:1 citrate-Fe3+ complex is likely, impacting Fe3+ binding constants to transferrin.
- Plasma transferrin competes with citrate for both Fe3+ and Al3+ in the blood.
Conclusions:
- Ingesting aluminum-containing antacids with citrus products poses risks due to Al3+-citrate complex formation.
- Accurate assessment of Fe3+ binding to transferrin requires accounting for citrate competition.
- Plasma transferrin plays a crucial role in sequestering Al3+ and Fe3+ from citrate in circulation.