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Nitrosyl hemoglobin: EPR components at low temperatures
E Wajnberg1, M P Linhares, L J el-Jaick
1CBPF/CNPq, Rio de Janeiro, Brasil.
European Biophysics Journal : EBJ
|January 1, 1992
Summary
Electron paramagnetic resonance (EPR) spectroscopy reveals temperature-dependent changes in nitrosyl hemoglobin. Phonon interactions influence the NO orientation within the heme plane, affecting spectral components.
Area of Science:
- Biophysics
- Chemical Physics
- Spectroscopy
Background:
- Nitrosyl hemoglobin (HNOb) is a crucial molecule in biological systems.
- Understanding its structural dynamics is key to elucidating its function.
- Electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for studying paramagnetic species.
Purpose of the Study:
- To investigate the temperature-dependent behavior of the EPR spectrum of nitrosyl hemoglobin.
- To elucidate the relaxation mechanisms governing nitrosyl hemoglobin.
- To understand the influence of phonon interactions on the NO orientation within the heme plane.
Main Methods:
- Electron paramagnetic resonance (EPR) spectroscopy was employed.
- Measurements were conducted across a temperature range of 7.5 K to 104 K.
- Power saturation studies were performed to analyze spectral components.
Main Results:
- The EPR spectrum exhibits at least three components (A, B, and C) with distinct temperature and power dependencies.
- Component A decreases with increasing temperature.
- Component B disappears around 30 K, being replaced by component C, indicative of phonon-induced changes in NO orientation.
Conclusions:
- The relaxation of component A follows the Orbach mechanism with an energy of 28 cm-1.
- Phonon-induced alterations in the NO orientation relative to the heme plane are responsible for the observed spectral changes.
- This study provides insights into the dynamic behavior of nitrosyl hemoglobin at low temperatures.