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Haem binding to horse spleen ferritin
1Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, UK.
FEBS Letters
|December 10, 1990
Summary
Horse spleen ferritin, unlike previously thought, can bind 15-17 haems per 24 subunits. This finding highlights a shared characteristic with bacterioferritin, impacting our understanding of iron metabolism.
Area of Science:
- Biochemistry
- Protein Structure and Function
- Metalloproteins
Background:
- Horse spleen ferritin is a protein shell composed of 24 subunits.
- Extracted horse spleen ferritin typically lacks haem groups.
- Bacterial ferritins (bacterioferritins) can bind up to 24 haem groups via methionine residues.
Purpose of the Study:
- To investigate the haem-binding capacity of horse spleen ferritin.
- To compare the haem-binding properties of animal ferritin with bacterioferritin.
- To assess the implications of haem binding for ferritin's role in iron metabolism.
Main Methods:
- Spectrophotometric analysis to quantify haem binding.
- Characterization of haem binding affinity (apparent association constant).
- Investigation of factors influencing haem binding (core presence, haem oxidation state).
Main Results:
- Horse spleen ferritin binds 15-17 haem groups per 24 subunits.
- The apparent association constant for haem binding is 2.2-3.2 x 10(4) M-1.
- Haem binding is independent of the ferritin core and the haem's oxidation state.
Conclusions:
- Animal ferritin (horse spleen ferritin) possesses significant haem-binding capabilities.
- This finding establishes a functional similarity between animal ferritin and bacterioferritin.
- The ability to bind haem may be crucial for the physiological roles of ferritin in iron uptake and release.