Question

The T to R state conformational change of hemoglobin: ____________

a. can occur when oxygen binds at any one of the four heme groups of hemoglobin.

b.can occur when ionic bonds stabilizing the T-state are broken.

c. would be less likely to occur if the covalent bond between the proximal His and the heme were broken.

d. would be more likely to occur if Lys C5 were mutated to a Glu.

e. All of the above are true.

Answer 1

The T to R state conformational change in haemoglobin is influenced by oxygen binding, ionic bond disruption, and structural mutations, with each factor contributing to haemoglobin's oxygen binding affinity.

Step-by-step explanation:

The conformational change from the T (tense) to R (relaxed) state of haemoglobin can be influenced by the binding of oxygen to the heme groups, the breaking of ionic bonds stabilizing the T-state, or mutations that affect hemoglobin's structure and its binding properties. When oxygen binds to any one of the four heme groups, it can initiate the T to R state transition. Additionally, mutations in haemoglobin, such as a change from Lys C5 to Glu, can affect the structure and the ionic interactions within the protein, potentially making the transition to the R state more likely. However, breaking the covalent bond between the proximal His and the heme, which is crucial for oxygen binding, would likely hinder the conformational change to the R state. Overall, the factors that contribute to the T to R state transition of haemoglobin are complex and interrelated.

Answer 2

All of the provided statements (a through d) regarding the T to R state conformational change of hemoglobin are true, and this transition is facilitated by oxygen binding and structural changes within the hemoglobin molecule.

Step-by-step explanation:

The T to R state conformational change of hemoglobin: e. All of the above are true.

This conformational change in hemoglobin can be triggered by oxygen binding at any one of the four heme groups (a), and is facilitated when ionic bonds stabilizing the T-state are broken (b). If the covalent bond between the proximal His and the heme were broken (which is crucial for the binding of oxygen), the conformational change to the R state would be less likely (c). Moreover, mutating Lys C5 to a Glu, which would affect the salt bridge interactions within hemoglobin, could influence the likelihood of the transition to the R state (d).

When oxygen binds to one of the heme groups in hemoglobin, it leads to structural changes that facilitate further oxygen binding due to a process known as cooperativity. As oxygen continues to bind, hemoglobin transitions from the low-affinity T (tense) state to the high-affinity R (relaxed) state. This mechanism is crucial for the efficient pickup and delivery of oxygen by hemoglobin throughout the body.