Haemoglobin Flashcards
Explain the structure of haemoglobin
1- globin polypeptide chains (2a,2b)
2- 4 heme groups (fe and porphyrin ring)
Explain the fe when oxygen is bound and deoxygenated
Fe2+ = ferrous = absent o2
Fe3+= ferric = o2 is bound
What colour is heme when it is oxygenated
Red
What are the 4 types of globin polypeptides
Alpha
Beta
Gamma y
Delta
Explain the 4 types of haemoglobin
HbA= 2 a , 2 b
Hba2= 2 a , 2 delta
Hbf = 2a, 2 y
Hbh = 4 b (a thalassemia)
what 2 things determine affinity for o2
Ppo2 (when high = high affinity)
Number of free binding sites (if 1 bound = more chance of others due to cooperative binding)
What are the 2 states Hb can be in
T taut state = high dissociation , low affinity
R relax state = high affinity , high association (in high ppo2)
Where is Hb likely to be in taut state
Low ppo2 areas like cell tissue
Other than o2, what else can bind to haemoglobin
Co2
H+ from carbonic acid
CO
NO
What does H from carbonic acid do (at cell tissues)
Lowers ph in blood and this causes Taut state of haemoglobin with low affinity and high dissociation
Why is binding of NO important
Regulatory molecule , it helps dilation of capillaries due to binding to guanylyl cyclase
What happens if CO binds
Prevents o2 dissociation and causes death
What are haemoglobinopathies
Changes to globins which are abnormal eg mutations via sickle cell anemia
What causes sickle cell anemia homozygous
Mutation in beta globin gene
The change to valine causes aggregation with others to form oligomers WHEN OXYGEN DISSOCIATES FROM THE B GLOBIN
What is the haemoglobin called in sickle cell anemia
HbS
