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Characterization of nonsymbiotic tomato hemoglobin
A Iulia Ioanitescu1, Sylvia Dewilde, Laurent Kiger
1Departments of Physics and Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
Biophysical Journal
|July 26, 2005
Summary
Nonsymbiotic tomato hemoglobin (SOLly GLB1) forms a dimer with high oxygen affinity. Its unique heme iron coordination and histidine ligation differ from vertebrate hemoglobins, revealed by advanced EPR techniques.
Area of Science:
- Plant biochemistry
- Biophysics
- Molecular biology
Background:
- Nonsymbiotic plant hemoglobins play roles beyond oxygen transport.
- Understanding their structure-function relationship is crucial for plant physiology.
Purpose of the Study:
- To characterize the structure and heme coordination of tomato hemoglobin SOLly GLB1.
- To investigate its ligand binding properties and compare it with other hemoglobins.
Main Methods:
- Ultraviolet/visible spectroscopy
- Resonance Raman spectroscopy
- Continuous wave and pulsed electron paramagnetic resonance (EPR), including HYSCORE measurements.
Main Results:
- SOLly GLB1 forms a dimer with high oxygen affinity.
- Deoxy ferrous form shows mixed penta- and hexacoordination; ferric form exhibits bis-histidine ligation.
- Pulsed EPR revealed a unique histidine plane rotation in the ferric form.
- Ligand binding kinetics indicate partial hexacoordination in the ferrous state.
Conclusions:
- Tomato hemoglobin SOLly GLB1 possesses distinct structural and coordination features compared to vertebrate hemoglobins.
- These findings provide insights into the functional diversity of nonsymbiotic plant hemoglobins.