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Conformational changes in proteins induced by low temperatures: an infrared study
H L Casal1, U Köhler, H H Mantsch
1Division of Chemistry, National Research Council of Canada, Ottawa.
Zeitschrift Fur Naturforschung. C, Journal of Biosciences
|November 1, 1987
Summary
Infrared spectroscopy reveals that hemoglobin undergoes reversible conformational changes, including alpha-helical distortions, upon cooling. Myoglobin shows smaller effects, and these changes do not occur in frozen solutions.
Area of Science:
- Biophysics
- Structural Biology
Background:
- Hemoglobin and myoglobin are crucial oxygen-binding proteins.
- Understanding their structural dynamics under varying conditions is vital for biochemical research.
Purpose of the Study:
- To investigate the conformational changes in hemoglobin and myoglobin using infrared spectroscopy.
- To determine the effect of temperature on the secondary structure of these proteins.
Main Methods:
- Infrared spectroscopy was employed to analyze hemoglobin (met-hemoglobin) and myoglobin.
- Measurements were taken across a temperature range from -110°C to 30°C in hydroalcoholic solutions.
Main Results:
- Cooling hemoglobin solutions induced a conformational change, evidenced by a new band at 1665 cm-1, suggesting alpha-helical structure distortions.
- Myoglobin exhibited less pronounced effects compared to hemoglobin.
- These temperature-induced conformational changes were fully reversible and absent in frozen aqueous solutions.
Conclusions:
- Hemoglobin's alpha-helical structure is sensitive to temperature changes in hydroalcoholic solutions.
- The observed conformational flexibility of hemoglobin differs from that of myoglobin.
- The reversibility of these changes highlights the dynamic nature of protein structures.