Interaction of Copper and Zinc with Peptides in Superoxide Dismutase
Author Information
Author(s): Alexandra Myari, Gerasimos Malandrinos, John Plakatouras, Nick Hadjiliadis, Imre Sovag
Primary Institution: University of Ioannina, Department of Chemistry, Ioannina, Greece
Hypothesis
The study investigates how Cu(II) and Zn(II) interact with specific peptides at the active site of Cu,Zn-superoxide dismutase.
Conclusion
The study found that Cu(II) forms more stable complexes with the peptides than Zn(II), suggesting a modulating role for Cu(II) in enzyme activity.
Supporting Evidence
- Cu(II) complexes with His-Val-His are thermodynamically more stable than Zn(II) complexes.
- The presence of histidine at the N-terminus results in histamine type coordination for both peptides.
- At low pH, a kinetically stable and a kinetically labile Zn(II) complex were observed.
- The stabilizing effect of the aspartyl side chain of His-Val-Gly-Asp results in the formation of a macrochelate.
- Deprotonation and coordination of amide nitrogens occurs at high pH, leading to distorted complexes.
Takeaway
The researchers looked at how two metal ions, copper and zinc, interact with small protein pieces in an important enzyme that helps protect cells from damage.
Methodology
The interactions were studied using potentiometric and spectroscopic methods including visible, EPR, and NMR.
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