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T-wave Ion Mobility-mass Spectrometry: Basic Experimental Procedures for Protein Complex Analysis
Published on: July 31, 2010
Correlation between hemichrome stability and the root effect in tetrameric hemoglobins.
Alessandro Vergara1, Marisa Franzese, Antonello Merlino
1Department of Chemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Naples, Italy.
Biophysical Journal
|August 5, 2009
Summary
Antarctic fish hemoglobins (Hbs) at acidic pH show unique iron forms, including a high-spin Fe(III) state in Root-effect Hbs. This reveals a correlation between the Root effect, hemichrome stability, and higher peroxidase activity.
Area of Science:
- Biochemistry
- Structural Biology
- Fish Physiology
Background:
- Hemoglobin (Hb) oxidation produces Fe(III) forms crucial for biochemical and physiological functions.
- Antarctic notothenioid fishes possess unique Hb properties adapted to cold, low-oxygen environments.
Purpose of the Study:
- To investigate the structural and functional characteristics of ferric tetrameric Hbs from Antarctic notothenioid fishes at acidic pH.
- To elucidate the relationship between the Root effect, hemichrome formation, and peroxidase activity in these Hbs.
Main Methods:
- Combined Electron Paramagnetic Resonance (EPR) spectroscopy and X-ray crystallography.
- Analysis of six ferric tetrameric Hbs isolated from Antarctic fish species (T. bernacchii, T. newnesi, G. acuticeps, C. gobio).
- Structural determination of the ferric Hb from T. bernacchii at acidic pH and 1.7 Å resolution.
Main Results:
- EPR analysis revealed the coexistence of aquomet form and two hemichromes in all studied Hbs at acidic pH.
- A significant amount of pentacoordinate (5C) high-spin Fe(III) form was exclusively found in Hbs exhibiting the Root effect.
- X-ray crystallography confirmed the 5C high-spin Fe(III) state in both alpha- and beta-chains of the T. bernacchii Hb at acidic pH.
- Antarctic fish Hbs displayed higher peroxidase activity compared to mammalian and temperate fish Hbs.
Conclusions:
- The Root effect and hemichrome stability at acidic pH are intrinsically correlated in tetrameric Hbs.
- Partial hemichrome states in tetrameric Hbs do not eliminate the need for peroxide protection, contrary to findings in monomeric Hbs.
- These findings offer insights into Hb adaptation in Antarctic fishes and their biochemical functions.
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