role of hemoglobin and myoglobin in biological sys ,heamoglobin ,myoglobin ,oxygen carrier ,oxygen storage ,oxygenation ,hill constant ,binding constant of myoglobin

1. Role of hemoglobin and
myoglobin in biological
systems
CECH-612
BY- Ms MAYURI R SOMPURA
UNIT-4 A
BY- Ms MAYURI R SOMPURA 1

2. OXYGENATION :-
• Hemoglobin pics oxygen from lungs and carries it to muscle tissues
via circulatory system.
• The oxygenated hemoglobin transfers oxygen to myoglobin present in
the muscle tissues where it remains stored as such till transferred to
other oxygen acceptors for performing metabolic actions in the
biological system.
• Hemoglobin also carries carbon dioxide from worked up muscle tissue
to lungs.
• This is done by certain side chains present on the polypeptide chains
present on the polypeptide chains of hemoglobin.
• The heme group of hemoglobin are not involved in flushing out
carbon dioxide from the muscles.
BY- Ms MAYURI R SOMPURA 2

3. OXYGENATION :-
• Oxygenation of myoglobin may be represented as :-
Mb + O2 ⇌ MbO2
So that : k =
𝑀𝑏𝑂2
𝑀𝑏 [𝑂2]
• f =fraction of myoglobin molecules bearing oxygen
• p =equilibrium partial pressure of oxygen
k =
𝑓
1 − 𝑓 𝑝
f =
𝑘𝑝
1 − 𝑘𝑝
K = binding constant of myoglobin in oxygen.
BY- Ms MAYURI R SOMPURA 3

4. OXYGENATION :-
• Hemoglobin with its four myoglobin like sub-units exhibit more
complex behavior.
• It follows the equation :
k =
𝐻𝑏 𝑂2 4
𝐻𝑏 𝑂2 4
f =
𝑘𝑝𝑛
1 − 𝑘𝑝𝑛
n = Hill constant
BY- Ms MAYURI R SOMPURA 4

5. OXYGENATION :-
• Its exact value depend upon the pH of the biological system.
• Its value is found to be 2.8 in pH range of physiological importance in
the muscle tissues.
• If value of n = 1, it means oxygen intake by one heme group of
hemoglobin is totally independent on oxygen intake of its other three
heme groups.
• If value of n = 4, it means Hb and Hb(O2)4 remain ultimate
participants in oxygenation of hemoglobin.
• If vale of n is between 1 & 4 ( as in present case n = 2.8) means the
attachment of oxygen group to one heme group of hemoglobin
progressively increases its tendency to bind with the subsequent heme
group of hemoglobin.
BY- Ms MAYURI R SOMPURA 5

6. OXYGENATION :-
• The phenomenon where addition of oxygen toone heme group
facilitates its addition, to other heme groups of hemoglobin is known
as cooperativity effect.
• Thus a value of 4 for n would reperesent the maximum cooperativity
effect.
BY- Ms MAYURI R SOMPURA 6

7. OXYGENATION :-
BY- Ms MAYURI R SOMPURA 7

8. OXYGENATION :-
• It can be seen from the graph that the partial pressure prevailing in the
lungs which is around 100-120 mm Hg, both hemoglobin and
myoglobin are completely saturated with oxygen.
• At low partial pressure of oxygen prevailing in muscles 20-40 mmHg,
hemoglobin is much pooer oxygen binder compared to myoglobin.
• Hence in muscles where myoglobin is already present, oxygenated
hemoglobin passes on its oxygen to myoglobin.
• The working muscles consume this oxygen to produce energy and
carbon dioxide.
BY- Ms MAYURI R SOMPURA 8

9. OXYGENATION :-
• The binding power of hemoglobin with oxygen is pH dependent.
• This is called Bohr effect.
• The binding power of hemoglobin decreases with the decrease in pH.
• The transfer decrease with decrease with pH.
• Hence, the transfer of oxygen from oxygenated hemoglobin to
myoglobin is more efficient in the working muscles where the carbon
dioxide concentration is higher than in the resting muscles.
• Carbon dioxide being acidic, decreases pH.
BY- Ms MAYURI R SOMPURA 9

10. Assignment :-
1. Write a note on : biological role of myoglobin and hemoglobin.
BY- Ms MAYURI R SOMPURA 10