Crocodile Hemoglobin Oxygen & HCO3- Binding: Effects & Function

[Momentum09]

Homework Statement

I was given the oxygen binding curves for human and crocodile hemoglobins, with the crocodile having a higher affinity for oxygen at p50.
My questions are,
1) Crodocile hemoglobin does not bind BPG. Instead, deoxyhemoglobin preferentially binds to HCO3-. How does bicarbonate binding affect the p50 of crocodile hemoglobin binding to oxygen?
2) How does the crocodile deoxyhemoglobin's affinity for HCO3- help it feed?

Homework Equations

1) I know that BPG decreases the affinity of hemoglobin for oxygen, so in the absence of BPG (in the case of the crocodile), the oxygen is tightly bound and would not release. What does bicarbonate and deoxyhemoglobin have to do with this process?

The Attempt at a Solution

Can someone please give me hints as to how to approach this problem? If you can explain the concepts to me that would be great!
Thank you so much!

 

[Ygggdrasil]

1) If deoxyhemoglobin preferentially binds to bicarbonate, how will the presence of bicarbonate affect oxygen binding? Will it increase hemoglobin's affinity for oxygen or decrease it?

2) Bicarbonate ions are a product of dissolved CO₂.

 

[epenguin]

Part of understanding this: know that the crocodile kills land animal prey not by biting it but by dragging it underwater and drowning it. I am not sure that its nostrils are not often underwater when hunting too. Anyway it can stay totally underwater for up to an hour as far as I remember. Can live without air longer than the prey.