Haemoglobin Flashcards
What two forms does haemoglobin exist in? How do they differ?
T/Tense state
R/Relaxed state **COME BACK TO
Which state of Hb has a lower affinity for O2?
T state
Which state of Hb has a higher affinity for O2?
R state (Think relaxed hippy, welcoming and let's everyone in, someone's who's tense doesn't)
Does fetal Hb have a lower or higher affinity for oxygen than maternal Hb? Why?
Higher affinity because it is less sensitive to 2,3-BPG
Will the Bohr effect shift the oxygen dissociation curve to the right or left?
To the right (lower affinity)
What agents bring about a shift to the right in a O2 dissociation curve? What change in affinity do they create?
CO2, 2,3-BPG, H+ all lower affinity for oxygen
What is the benefit of feotal Hb having a higher affinity for O2 than maternal?
When the two blood supplies are near (IE in placenta) the O2 will travel from maternal to feotal blood.
What is the effect of CO poisoning?
CO binds to Hb sub units- TF reducing no. available to O2.
When CO binds it increases the affinity of Hb for O2 TF when O2 binds it isn’t easily released.
What would the effect of a drop in pH be on oxygen binding/release?
H+ bind to Hb molecule, by binding causes the creation of bonds which bring the subunits closer together–> promotes T state + lowers affinity for O2. O2 is more easily released.
What would the effect of a drop in pH be on oxygen dissociation?
Curve shifts to the right–> Bohr Shift
What would the effect of an increase in 2,3 BPG conc be on oxygen binding/release?
2,3 BPG binds to Hb molecule, causing bonds to form pulling sub units closer together and promoting T state- TF lower affinity for O2 TF O2 released more easily.
What may cause an increase in 2,3 BPG?
More 2,3 BPG is released at higher altitude
What would the effect of an increase in 2,3 BPG be on oxygen dissociation?
Curve shifts to the right- Bohr effect. Lower affinity for O2
What is another name for 2,3 BPG?
2,3 DPG (2,3 bi/diphosphoglycerate)
What is the benefit of the Bohr Effect?
Useful in metabolically active tissues- allows Hb to give up oxygen easier to supply rapidly respiring tissues with enough O2 to continue
What conformational change brings about the T state of Hb?
When no oxygen is bound to Hb, the two αβ diners form ionic and H bonds which restrain movement and lower affinity of Hb for O2.
What conformational change brings about the R state of Hb?
Once an O2 binds to a Hb subunit, some ionic and H bonds break raises the affinity of the Hb for O2 making it easier for other O2 to bind.
What is cooperative binding?
Once one O2 molecule binds to a Hb subunit, it brings about a conformational change (by breaking some ionic and H bonds) which stabilises Hb’s R state, raising the affinity for O2 meaning it is easier for other O2 molecules to bind.
Which state is deoxygenated- T or R?
T state
Which state is oxygenated- T or R?
R state
What is the benefit of having Fe ions bound to a protein like Hb rather than floating on its own?
Fe embedded in protein keeps it hidden and TF protected against damage from H2O. Which would lower its binding ability.
How would you describe the dissociation curve of O2 for myoglobin?
Hyperbolic
What is myoglobins function?
Designed to bind to the O2 that has been released by Hb, store it within muscles and then release it upon demand.
How can myoglobin be a clinical marker?
Only present in muscles (eg heart and skeletal) TF when it’s present in blood stream- suggests muscle injury
