Myoglobin and Hemoglobin Structure and Function

These flashcards cover important concepts related to the structure and function of myoglobin and hemoglobin, including their cooperative binding and conformational changes.

What structural change occurs in hemoglobin when oxygen binds?

Binding of oxygen alters the structure of the hemoglobin tetramer, changing it from the T (tense) state to the R (relaxed) state.

What is cooperativity in the context of oxygen binding to hemoglobin?

Cooperativity is the phenomenon where the first binding event increases the affinity at remaining sites.

What type of binding curve does hemoglobin exhibit for oxygen?

Hemoglobin has a sigmoidal binding curve for oxygen.

What is indicated by a Hill coefficient (nH) greater than 1?

A Hill coefficient greater than 1 indicates positive cooperativity in ligand binding.

What are the two conformations of hemoglobin?

The two conformations of hemoglobin are the R state (higher affinity for O2) and the T state (lower affinity for O2).

How does oxygen binding affect the ion pairs in hemoglobin?

Oxygen binding triggers a conformational change that results in breaking some ion pairs and forming new ones, stabilizing the R state.

What is the role of ion pairs in stabilizing the T state of deoxyhemoglobin?

Ion pairs stabilize the T state of deoxyhemoglobin by providing more interactions.

What happens during the T to R transition in hemoglobin?

During the T to R transition, the αβ subunit pairs slide past each other and rotate, causing the pocket between the β subunits to narrow.

What does a sigmoidal Hill plot indicate about binding properties?

A sigmoidal Hill plot indicates cooperative binding, where the binding of one ligand affects the binding of others.

What is the significance of the p50 value in hemoglobin?

The p50 value indicates the partial pressure of oxygen at which hemoglobin is 50% saturated, reflecting the affinity for oxygen.