Protein 2 Flashcards
Explain the Hb subunit contacts ?
There is alpha 1 & alpha 2 and beta 1 & beta 2. There are more interactions between cyan and coral (alpha 2 and beta 2) than cyan and blue (alpha 2 and beta 1)
Does alpha1/beta2 interface change ?
Changes occur at alpha1/beta2 interface
Does alpha1/beta1 interface change ?
Alpha1/beta1 unchanged
The energy in the formation of the Fe-O2 bond formation drives ?
The T to R transition
Haemoglobins O2 -binding Cooperativity derives from?
The T to R Conformational shift
The Fe of any subunit cannot move into its haem plane without ?
The reorientation of its proximal His so as to prevent this residue from bumping into the porphyrin ring
The proximal His is so tightly packed by its surrounding groups that it can not ?
Reorient unless this movement is accompanied by the previously described translation of the F helix across the haem plane
Small change in pH of environment leads to ?
Large change in binding affinity
Higher pH i.e. lower [H+] promotes ?
Tighter binding of oxygen to haemoglobin
Lower pH i.e. higher [H+] permits ?
The easier release of oxygen from haemoglobin
In capillaries (low pO2), the H+ is taken up by ?
Hb- releases O2 and also drives forward reaction
In lungs (high pO2),O2 binding leads to ?
H+ released from Hb and drives reverse reaction and release of CO2
Bicarbonate is 100 x more soluble than ?
CO2. Otherwise CO2 would form bubbles in blood!
Deoxyhaemoglobin binds CO2 as ?
Carbamate
What does high [CO2] in capillaries ?
Stimulates Hb to release O2
What also affects Hb affinity for O2 ?
[Cl-]
T-> R state involves breaking of ?
Salt bridges driven by Fe2 –O2 bond formation
BPG binds to ?
Central cavity of deoxy Hb on its 2 fold between two b chains
When is there no room for BPG ?
In R state
The transition from deoxyhemoglobin (T state) to oxyhemoglobin (R state) occurs ?
Upon oxygen binding
Explain Heterozygous individuals and Homozygous individuals with Sickle Cell Anaemia (SCA) ?
Heterozygous individuals – carriers
Homozygous individuals – diseased
SCA results from ?
Defective Haemoglobin
- Haemoglobins stick together
- Red blood cells damaged
What will this therefore lead to ?
Complications from low oxygen supply to tissues;
- Pain, organ damage, strokes, increased infections, etc.
Incidences are highest among ?
Among Africans and Indians.
- Heterozygotes protected from Malaria
Hydrophobic Val replaces?
Hydrophobic Glu on β chain
