Lecture 12 - O2 Transport and Storage by Haemoglobin and Myoglobin Pt. II Flashcards
What does the haem look like in deoxyhaemoglobin?
dished
What happens to the haem upon the formation of oxyhaemoglobin?
oxygen flattens the haem and pulls HisF8 and helix F toward the binding site
What will weaken oxygen binding?
anything that keep helix F away from the binding site
What are conformational changes?
shifts in the orientation of protein secondary elements
What are some mechanisms that work together to shift between T and R states
- Allosteric regulation
- pH
- Physiological/genetic changes
What can change the balance of T & R state haemoglobin?
Conformational changes
When is co-operativity prominent?
In the presence of allosteric inhibitors of binding
What stabilises the T-state?
allosteric inhibitors BPG, CO2, and H+. this allows better cooperativity
What state is ‘stripped’ haemoglobin predominantly in in the absence of inhibitors?
R-state, shows little co-operativity
What is Haemoglobin allosterically controlled by?
2,3 - biphosphoglycerate (BPG)
How does BPG bind to deoxy-Hb?
electrostatic interactions
What does BPG do to Hb?
stabilises Hb in the deoxy T-state reducing oxygen affinity
How is BPG produced?
during respiration in peripheral tissues
What does BPG promote?
oxygen release where it is required
What does CO2 do to oxygen affinity?
reduce oxygen affinity