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Kinetics of human apohemoglobin dimer dissociation
1Department of Chemistry, College of Arts and Sciences, University of Massachusetts at Lowell 01854.
Biochemical and Biophysical Research Communications
|March 30, 1994
Summary
Human apohemoglobin dimer dissociation was studied using heme chain exchange. The dimer dissociation rate constant was determined to be 0.54 h-1, with optimal conditions at pH 7.0 and 20°C.
Area of Science:
- Biochemistry
- Protein dynamics
- Hemoglobin research
Background:
- Human apohemoglobin exists as a dimer, crucial for its function.
- Understanding dimer dissociation is key to protein stability and function.
Purpose of the Study:
- To investigate the dimer dissociation kinetics of human apohemoglobin.
- To determine the rate constant and factors influencing apohemoglobin dimer dissociation.
Main Methods:
- Heme chain exchange technique was used to monitor dimer dissociation.
- Kinetic analysis of semihemoglobin formation over time.
- pH and temperature dependency studies were conducted.
Main Results:
- Dimer dissociation followed first-order kinetics with a rate constant of 0.54 h-1.
- Dissociation rate showed a maximum at pH 7.0, suggesting a role for histidyl residues.
- Energy of activation was calculated as 7.2 kcal/mol.
Conclusions:
- Alpha G-beta G helical pairing significantly contributes to apohemoglobin dimer integrity.
- The study provides insights into the stability and dissociation mechanisms of hemoglobin dimers.