Proteins-- Haemoglobin

Question 1

What is the structure of Haemoglobin?

Answer 1

Two a-chains and two b-chains forming a tetradedral with Mr of 64,000

Question 2

Why is the tertiary formation of HG important?

Answer 2

Transportation of H+, CO2 and O2,

Question 3

What is O2 binding regulated by?

Answer 3

H+, CO2, 2,3-BPG as allosteric

Question 4

What is the primary structure of Deoxyhaemoglobin?

Answer 4

141 AA a chains
146AA beta chains

Question 5

Positive Co-operation

Answer 5

This is where change in shape of the first subunit makes bindig of the second substrate easiet.

Question 6

Why is S1 o2 affinity important?

Answer 6

HG becomes a more effcienct transporter

Question 7

What is HG p50 in HG?

Answer 7

26.6 WHILST mg 2.75

Question 8

Why are HG regulators important?

Answer 8

Pure HB binds O2 too tightly for physiological needs

Question 9

Bohr Effect

Answer 9

This is the property of vertebrate HG where pH changes affect HB-oxygen affinity t osuppport oading and unloading

Question 10

How does lactic acid regulate Bohr Effect?

Answer 10

Formed on exercising muscles and venous blood acidificaiton occurs from CO2 dissolution and ioniziation increasing H+

Question 11

What happens to ODC under acidic conditions?

Answer 11

Shifts to right and more O2 is released

Question 12

Oxygen Dissociation Cruve

Answer 12

This is the expression of the relationship between the partial pressure of O2 and O2 saturation of HG

Question 13

How does 2.3-BPG reglate?

Answer 13

Produeced by RBC by glycosist at 4-5mm concentrations

Question 14

Why is 2,3-BPG glycosis generation useful?

Answer 14

Generated by activity usin O2 thus signalling more oxygen required

Question 15

What is the physiological importance of 2,3-BPG?

Answer 15

In its absence, PO2 would not allow dissassociation of O2

Question 16

How does temperature affect ODC?

Answer 16

Shifting it to the right thus increasing release of O2 in active muscle

Question 17

Jpw dpes R amd T state conformationally differ?

Answer 17

Beta chain Fe distance from one another decrease from 3.99 to 3.34

Question 18

What is T State contrained by?

Answer 18

Hydrophobic bonds and 8 electrostatic bonds involving the CTD AA of each subnit

Question 19

What allows electrosttic bond formation in both chains?

Answer 19

Penultimate Tyr residue held within a pocket by H-bonding to a val

Question 20

What is the T state stabilised by?

Answer 20

2,3-BPG binding with 8 elec trostatic bonds

Question 21

What is the structure of the Haem in DHG?

Answer 21

F8 binds Fe above the porphyrin ring by 0.06nm

Question 22

How does O2 affect haem group conformaiton?

Answer 22

Brings Fe 0.039nm closer to porphyrin plan, dragging His F8 to Helix F with EF corner and FG corner resulting in breakage of 8 electrostatic bonds

Question 23

How does Tyr break the 8 electrostatic bonds?

Answer 23

Emergence of Tyr residues from the H-bonded pockets with valines breaking the bonds

Question 24

How do the A-B dimer change rein conformation changes?

Answer 24

Rotate 15 degrees with respect to one another

Question 25

Retinol

Answer 25

THis is an active form of Vit-A derived from b-carotenes stored in the liver

Question 26

What are the functions of Vitamin A?

Answer 26

Anti-oxidant, steroid hormone and night vision