(06) Hemoglobin Transition 1 to 2

Oxygen Transport and Hemoglobin Affinity

• Key Functions of Hemoglobin

  • Transport Oxygen: Binds oxygen in the lungs.

  • Release Oxygen: Releases oxygen in body tissues.

  • Affinity Variation: High affinity for oxygen in lungs, low affinity in tissues based on partial pressure of oxygen.

Sigmoidal Dissociation Curve

• Shape and Functionality:

  • The sigmoidal shape allows for effective oxygen transport.

  • Partial Pressure Influence:

    • High partial pressure of oxygen in lungs.

    • Lower partial pressure of oxygen in body.

  • Steep segment of the curve enables hemoglobin to release a significant amount of oxygen with minor decreases in partial pressure.

Cooperative Binding Mechanism

• Heme Groups Interaction:

  • Hemoglobin consists of four heme groups, each capable of binding one oxygen molecule.

  • Binding of oxygen in one heme group affects affinity in others (cooperative binding).

• Affinities During Oxygen Binding:

  • Low Affinity State:

    • When no oxygen is bound, hemoglobin has a low affinity for oxygen.

  • Increasing Affinity:

    • Binding of the first oxygen molecule enhances the ease of binding for subsequent molecules.

    • Increasing affinity sequence:

      • After 1st oxygen binds: Affinity increases.

      • 2nd oxygen bound: Affinity increases further.

      • 3rd oxygen bound: Affinity can increase by a factor of 300 compared to the fully unbound state.

      • 4th oxygen binds very easily due to high affinity state.

Transitioning Hemoglobin Properties

• Molecular Mechanisms:

  • Exploration of how the initial binding of oxygen influences the molecular behavior and properties of hemoglobin.

  • Investigation into hemoglobin's changes as it circulates from lungs to body tissues and back.

• Conclusion:

  • Understanding hemoglobin's function in oxygen transport illustrates the remarkable adaptation of the protein to meet physiological needs.