Molecular Pathology Of Haemoglobin Flashcards
What percentage of Hb is in Hb A form?
97%
What percentage of of adult Hb is in HbA2 form?
2% (minor adult)
What percentage of adult Hb is in HbF form?
1% (Foetal)
What two enzymes reduce methaemoglobin?
Methaemoglobin reductase
Cytochrome b5 reductase
What percentage of Hb is in met form?
1-3%
Features of methaemoglobin
Oxidised to Fe3+
Does not bind oxygen
Chocolate brown
Name two pathologies of methaemoglobin
Cyanosis
Methaemoglobinaemia
How is met reduced by NAD(P)H?
An electron is donated by NADH and NADPH co factors where the H ion loses an electron to become H+ proton
How does the red cell burn sugar?
Glucose -> G6P -> Pyruvate -> lactate/lactic acid
Include intermediaries: NADPH, G6P dehydrogenase, 2,3-BPG, pyruvate kinase
List features of HbF
α2 γ2
High affinity for O2
Extracts oxygen from mothers blood
Level is highest at later stages of pregnancy; Declines after birth
In what conditions does the oxygen dissociation curve move to the right? (4)
Increased temp
Increased 2,3 BPG
Increased pCO2
Decreased pH
In homeostasis, what is the level of 2,3 BPG in the blood?
5mmol/L human RBCs
List features of 2,3-BPG
3 carbon isomer of a glycolysis IM
Binds less efficiently to oxygenated Hb
Binds with greater affinity to deoxygenated Hb when RBCs are near respiring tissue
Binding to partially deoxygenated Hb -> increased release of bound O2 molecules from the Hb tetramer
HbF - low affinity for 2,3 BPG
Describe the features of myoglobin
Oxygen carrying pigment of muscle
Not multimeric
No cooperative binding
Hyperbolic O2 dissociation curve
Whales and seals (fish) have high levels
What gives meat its brown colour?
Fe2+ -> Fe3+
