Myoglobin-Pyruvate Interactions: Binding Thermodynamics, Structure-Function Relationships, and Impact on Oxygen
Kiran Kumar Adepu1,2, Dipendra Bhandari1, Andriy Anishkin3
1Arkansas Children's Nutrition Center, Little Rock, AR 72202, USA.
International Journal of Molecular Sciences
|August 12, 2022
Summary
Pyruvate (PYR) and lactate (LAC) interact with myoglobin (Mb), affecting oxygen (O2) release. PYR binds deoxy-Mb more strongly than LAC, but releases less O2 from oxy-Mb, suggesting distinct roles in regulating O2 availability.
Area of Science:
- Biochemistry
- Protein-ligand interactions
- Metabolic regulation
Background:
- Myoglobin (Mb) functions in oxygen transport and nitric oxide metabolism.
- Glycolytic end-products like lactate (LAC) and pyruvate (PYR) may influence Mb activity.
- Understanding these interactions is crucial for comprehending oxygen homeostasis in tissues.
Purpose of the Study:
- To investigate the effects of pyruvate (PYR) on myoglobin (Mb) interactions.
- To compare PYR's effects with those of lactate (LAC) on Mb's oxygen (O2) binding and release kinetics.
- To evaluate PYR's affinity for both oxy- and deoxy-Mb states.
Main Methods:
- Isothermal titration calorimetry (ITC) to determine binding affinities.
- Circular dichroism (CD) spectroscopy to assess conformational changes.
- Oxygen (O2) kinetic studies to measure O2 release rates.
Main Results:
- PYR binds to both oxy- and deoxy-Mb with a 1:1 stoichiometry, similar to LAC.
- PYR exhibits higher affinity for deoxy-Mb compared to LAC, which prefers oxy-Mb.
- PYR interaction with oxy-Mb results in significantly less O2 release than LAC interaction.
Conclusions:
- Glycolytic end-products, PYR and LAC, differentially regulate Mb's oxygen binding and release.
- These findings support the hypothesis that PYR and LAC act as novel regulators of O2 availability in Mb-rich tissues.
- Metabolite interactions with Mb may impact tissue oxygenation states during varying metabolic conditions.
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