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Zinc forms complexes with higher kinetical stability than calcium, 5-F-BAPTA as a good example
P Csermely1, P Sándor, L Radics
1Institute of Biochemistry I., Semmelweis University School of Medicine, Budapest, Hungary.
Biochemical and Biophysical Research Communications
|December 15, 1989
Summary
Zinc ions (Zn2+) form more stable complexes than calcium ions (Ca2+), with longer lifetimes. This explains how zinc competes with calcium in cellular processes, even with lower concentrations.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Physiology
Background:
- Growing interest in zinc's biological roles, particularly in DNA-binding proteins with zinc-fingers.
- Zinc's ability to displace calcium ions (Ca2+) and influence calcium-mediated cellular processes.
Purpose of the Study:
- To measure the dissociation rates of zinc (Zn2+) and calcium (Ca2+) complexes with 5-F-BAPTA.
- To investigate the binding kinetics and stability of Zn2+ and Ca2+ with a calcium indicator.
Main Methods:
- Utilized two-dimensional 19F Nuclear Magnetic Resonance (NMR) exchange spectroscopy.
- Measured dissociation rates of Zn2+- and Ca2+-complexes with 5-F-BAPTA.
Main Results:
- The Zn2+-5-F-BAPTA complex exhibited a lifetime over five times longer than the Ca2+-5-F-BAPTA complex.
- Zn2+-complex demonstrated higher thermodynamical stability compared to Ca2+-complex.
Conclusions:
- The extended lifetime and enhanced stability of Zn2+-complexes contribute to zinc's ability to compete with calcium in cellular functions.
- This competition can occur despite potentially higher free calcium ion concentrations compared to free zinc ion concentrations.