Biochemistry from Dr. Dhiraj J. Trivedi S D M College of Medical Sciences and Hospital, Dharwad, India

1. Amino acid pool
[Reserve of amino acids ]
Nitrogen Account
Dr. Dhiraj J Trivedi

2. Q: Explain the amino acid pool of body.
Illustrate how it is maintained.
Short essay -- 5marks

3. What is amino acid pool?
• Reserved stock (Pool) of amino acids in
the plasma and tissue
• Approximately 100gm of amino acids
remain in dynamic state.
• Constantly replenished as they are utilised.

4. Amino acids
Pool
100 gm
Digestion of
dietary proteins
70 - 100 gm / day
Synthesis of
non essential
amino acids
[Concentration vary]
Degradation of
old body proteins
~ 300 - 400 gm / day
Influx / entry of
amino acids

5. Amino acids
Pool
100 gm
Synthesis of new proteins
~ 300 - 400 gm / day
Synthesis of
NPN
substances
Porphyrins
Creatine
Purines
Pyrimidines
Niacid,
Thytoid
hormone
~ 30 gm / dayCatabolised in liver
35 - 55 gm / day
Glycogenic
Glucose
Ketogenic
Fat
Energy,
CO2, H2O,
UREA
Outlet / Exit of
amino acids

6. Amino
acids
Pool
100 gm
Digestion of
dietary proteins
70 - 100 gm /
day
Synthesis of
non essential
amino acids
[Concentration
vary]
Degradation of
old body proteins
~ 300 - 400 gm /
day
Synthesis of new proteins
~ 300 - 400 gm / day
Synthesis of
NPN
substances
Porphyrins
Creatine
Purines
Pyrimidines
Niacid,
Thytoid
hormone
~ 30 gm / dayCatabolised in liver
35 - 55 gm / day
Glycogeni
c
Glucose
Ketogenic
Fat
Energy,
CO2, H2O,
UREA
In & out of
amino acids

7. Importance of Amino acid pool
• Allows High turn over of amino acids.
• Amino acids are made available, &
deficiency does not occur immediately.
• Constantly replenished by dietary proeins.
• Urea excretion is the index of Nitrogen
loss from body.
• It should be replenished by dietary protein
to maintain Nitrogen balance.

8. What is protein turn over?
• In health there is constant Degradation of
old and used proteins, Which is replaced by
the synthesis of new protein.
• In normal healthy individual about 300 to
400 gm of protein is turned over every
day.

9. Nitrogen Balance

10. What is Nitrogen balance?
• It is the comparison between Nitrogen intake
and Nitrogen loss from the body.
• Nitrogen balance is the index of growth / anabolic
status of the body.
• Proteins are the sole source of Nitrogen in body.
• 10 to 15 % of energy is derived from protein.
• But in absence of carbohydrates, amino acids are
used for energy need.
• As a result nitrogen is excreted / lost , in the form
of urea and NPN substances.

11. What is Nitrogen balance?
• Is a specific term, describes status of nitrogen
metabolism in Human body.
• Defined as a balance between amount of
Nitrogen intake in the form of dietary protein
• and
• amount of Nitrogen lost or excreted in the form
of Urea, Uric acid, Creatinine and small amount
of amino acids by an individual.

12. What is Nitrogen equilibrium?
• Nitrogen equilibrium means
• When
• Dietary intake = Daily loss through urine,
feces, skin
• Intake == Loss L=(U + F + S )
• Seen in health ,

13. What is positive Nitrogen balance?
• When
• Intake is greater than Loss --- Positive
Nitrogen balance
• I > L == Positive nitrogen balance
• Positive N2 Balance
• Growth, Pregnancy, Recovery from illness
• Hormones leads to positive nitrogen balance :
• Growth hormone, Insulin, Androgens

14. What is negative nitrogen balance?
• When
• Intake is less than Loss ---- Negative Nitrogen
balance
• I < L == Negative nitrogen balance
• Negative N2 Balance
• Chronic / Acute illness, Protein deficiency,
starvation
• Hormones leads to negative nitrogen balance :
• Corticosteroids, T4

15. Thank you
Maintain Money account & remain
Wealthy
Maintain Nitrogen /protein
Account & remain healthy