Nucleic acid Nucleic acids are the polymer of nucleotides (polynucleotides) held by 3’ and 5’ phosphate bridge. Nucleotide Nucleotide perform variety of functions in a living cells. They are composed of pentose sugar, phosphate and a nitrogenous base. Functions of Nucleotide Monomeric units of DNA and RNA Structural component of several coenzymes e.g. FAD, NADP+ Serve as carriers of high energy intermediates in the biosynthesis of carbohydrates, lipids and proteins Nucleotides are intimately involved in the energy reactions of the cell e.g. ATP Control several metabolic reactions by their action as allosteric regulators. Cyclic AMP amd cyclic GMP are the second messenger in hormonal functions. Nucleotide structure Biosynthesis of Purines Biosynthesis of Pyrimidine Disorder of Purine Catabolism of Purine

1. Nucleic Acid & Nucleotides
Prepared by: Pratishtha Sharma
M.Pharm. (Pharmacology)

2. What is Nucleic acid??
Nucleic acids are the polymer of nucleotides (polynucleotides)
held by 3’ and 5’ phosphate bridge.
What is Nucleotide??
• Nucleotide perform variety of functions in a living cells. They are
composed of pentose sugar, phosphate and a nitrogenous
base.

3. Functions of Nucleotides
 Monomeric units of DNA and RNA
 Structural component of several coenzymes e.g. FAD, NADP+
 Serve as carriers of high energy intermediates in the biosynthesis of carbohydrates, lipids and
proteins
 Nucleotides are intimately involved in the energy reactions of the cell e.g. ATP
 Control several metabolic reactions by their action as allosteric regulators.
 Cyclic AMP amd cyclic GMP are the second messenger in hormonal functions.

4. Structure
Pentose Sugar + Phosphate + Nitrogenous Base = Nucleotide
Nucleoside
(aromatic heterocyclic)
Purine Pyrimidines
Adenine Guanine

5. Biosynthesis of Purine

7. Biosynthesis of Pyrimidine

8. Disorder of Purine Metabolism :- Hyperuricemia &
Gout
 Hyperuricemia refers to an elevation in the serum uric acid concentration. This is sometimes associated with
increased uric acid excretion (Uricosuria).
 Gout is a metabolic disease associated with overproduction of uric acid.
 In severe hyperuricemia crystals of sodium urate get deposited in the soft tissues, particularly in joints. Such
deposits are commonly known as tophi. This causes inflammation in the joints resulting in a painful gouty
arthritis.
Treatment of Gout
Drug of choice is Allopurinol.
Allopurinol is structural analogue of hypoxanthine that competitively inhibits Xanthine oxidase and forms
Alloxanthine which is also a effective inhibitor of Xanthine oxidase.

9. Catabolism of Purine
 The end product of purine metabolism in humans is Uric Acid. The sequence of reactions in purine nucleotide
degradation is :
1. Nucleotide monophosphate (AMP,GMP & IMP) are converted to their nucleoside form (adenosine,
guanosine & inosine) by the action nucleotidase.
2. The amino group, either from AMP or adenosine, can be removed to produce IMP or inosine respectively.
3. Inosine and guanosine are respectively converted to hypoxanthine and guanine by purine nucleoside
phosphorylase.
4. Guanine undergoes deamination by guanase to form xanthine.
5. Xanthine oxidase is an enzyme which convert hypoxanthine to xanthine and xanthine to Uric acid