Hemoglobin 1

Question 1

What is the importance of Globins around the body

Answer 1

Increase the O2 saturation in blood
- saline saturation 0.2mmol/l
- satuation with hemoglobin 5mmol/l
+ myoglobin in muscles

Question 2

What are the properties of heme

Answer 2

• Prosthetic co factor
• 4 pyrrole rings forming planar shape
• Fe++ ion Coordinating 6 bonds, 4 to N on pyrrol, 1 to HisF8, 1 to O2
• reversable reaction
• Red due to orbitals

Question 3

What are the strcutural properties of myoglobin at each protein level

Answer 3

Primary: 150 AA long
Secondary: 8 alpha helix
teritary: globlin fold - contains hydrophobic pocket where heme binds
Quaternary: monomer

Question 4

What are the strcutural properties of hemoglobin at each protein level

Answer 4

Primary: 150 AA long
Secondary: 8 Alpha helix
teritary: Globlin fold - hydrophobic pocked = heme binding
Quaternary: Tetrimer - 2 alpha, 2 beta sub units

Question 5

How is O2 bound to hemoglobin
Does this effect shape

Answer 5

HisF8 Alpha helix binds to the Fe++ ion
O2 binds to the 6th coordinate of Fe++
- binding pulls heme from out of plane into plane
His from helix E binds to the other side of O2

Question 6

How to measure the amount of heme bound to O2

Answer 6

Beer-lamburts law - spectroscopy
Light absorbance, Increased with more O2
More red = more O2

Question 7

What are the two curves shown by myo and hemo globin

Answer 7

Myoglobin: Hyperbolic curve
Hemoglobin: sigmoidal curve

Question 8

When do myo and hemo globin get saturated and release O2

Answer 8

Myoglobin:
- saturated at low PP (muscles)
- released at very low pp
Hemoglobin:
- saturated at high pp (lungs)
- released at low pp

Question 9

What are the two factors which change O2 binding affinity

Answer 9

Allostery: monomer or oligomer
- binding to another site on the protein

Co-ordination: oligomer
- 1 chain impacts annother
2 models
- concerted = all conform together
- seqential = only effects neighbouring strands

Question 10

Wat are the properties of myoglobin

Answer 10

• Stored O2 in muscles
• Released when needed
• Hypobolic curve

Question 11

What are the properties of hemoglobin

Answer 11

• Carrys O2 around body + easy release at tissue
• T state = low binding affinity, R state = high binding affinity- more O2 bound heme units = Other heme units change to R state for unbound heme
• sigmasoidal
• Doesnt follow micheales menten kinetics