Digestion and Absorption of nucleic acids (Biochemistry)

In this section, we describe digestion and absorption of Nucleic Acids and Most of the slides are cited from:
1. Lippincott's Illustrated Review Biochemistry
2. U. Satyran Biochemistry
Dr. Haroon

1. Asst. Prof. Dr. Muhammad Haroon
MD, ECEA, MPH (JHSPH)

Head & Coordinator of MPH Program

Former Biochemistry Guest lecturer at SMS
medical college, India.
Email:[email protected]

2. Overview

e Nucleotides are both:
— Taken in diet
— Synthesized in the body

e Dietary nucleotides:

- Cannot be used in our body

e We are dependent exclusively on:

- Endogenously synthesized nucleotides . Digsetion 8
Absorption of Nucleic
Acids

3. Digestion of dietary Nucleic Acids

e In food, nucleotides are present mainly in form of:
- Nucleoproteins
e The protein part is degraded by:
- Proteolytic enzymes in the GIT
e The nucleic acids are hydrolyzed by:
- Nucleases
e Nucleases are present in:
- Pancreatic Juice
Digsetion 8.

Absorption of Nucleic
Acids

- Intestinal Secretion

4. Pancreatic Secretions

e It includes:
- Ribonucleases
- Deoxyribonucleases
- Breaks Phosphodiester Bond
e Ribonuclease:
- Hydrolyze RNA to oligonucleotides
e Deoxy-Ribonuclease:
- Hydrolyze DNA to oligonucleotides

Digsetion &
Absorption of Nucleic
Acids

5. Intestinal Secretions

e It includes:
- Phosphodiesterase
- Nucleotidases
- Nucleosidases
e Phosphodiesterase:
- Degrades oligonucleotides to mononucleotides
e Nucleotidases:

- Degrades Nucleotides to Nucleosides & Phosphates

Digsetion &
Absorption of Nucleic
Acids

6. Intestinal Secretions Cont..........

e The nucleosides may be either:
- Directly absorbed
- Or degraded to free bases and sugars by nucleosidases

Digsetion &
Absorption of Nucleic
Acids

7. Overview of Nucleic Acids
Digestion

Nucleic acids
(DNA, RNA)

Unchanged

Purines, Pyrimidines

Digsetion &
Absorption of Nucleic
Acids

8. Absorption of Nucleosides

e Nucleosides are absorbed by mucosal cells of
intestine through:
- Carrier Mediated Transport or simple diffusion
e In intestinal mucosal cell:
- They are broken down to their final end products
e The end products are released into:
— Circulation

e They are excreted in:

Digsetion &
Absorption of Nucleic
Acids

- Urine

9. References

e Harvey, Richard A., Ph. D. (2017). Lippincott's illustrated reviews:
Biochemistry. 7% Edition. Philadelphia :Wolters Kluwer Health,

e Murray, R. K. (2016). Harper's illustrated biochemistry. 31‘ Edition.
New York: McGraw-Hill.

e U. Satyanarayana, Biochemistry, Books and Allied (P) Ltd., Calcutta,
Fourth Edition

e The images are retrieved from: www.google.com/images

Digsetion &
Absorption of Nucleic
Acids

10. Thank You

sorption of Nucleic