This document discusses nucleotides, which are organic molecules that consist of a nucleoside and one or more phosphate groups. Nucleotides are the building blocks of DNA and RNA. It describes the components of nucleotides, including pentose sugars, phosphate groups, and nitrogenous bases. It also outlines the two pathways for nucleotide biosynthesis in cells: de novo synthesis, where nucleotides are synthesized from simple precursors, and salvage pathways, which recover bases and nucleosides from degraded DNA and RNA. The document provides details on purine and pyrimidine synthesis, including key enzymes and structural analog inhibitors that are used as anticancer drugs.

1. WELCOME

2. Muhammad Abdul Jalil
Department of Pharmacy,
University of Chittagong

3. NUCLEOTIDE
Nucleotides are organic molecules consisting of a
nucleoside( contain one nitrogenous base & a
pentose sugar) and one or more phosphate group.
Nucleotides are the monomer of DNA
(Deoxyribonucleic acid) and RNA (Ribonucleic acid)
both of which are essential bio-molecules within all
life-forms on Earth.

4. • Pentose sugar : Deoxyribose sugar
and Ribose sugar.
• Phosphate : Two nucleotide link-
up by phosphate group and create
polynucleotide.Ex-DNA,RNA.
• Nitrogenous base: One or two ring bases that contains Nitrogen
in the ring.Two types-
1. Purine base - larger double ring structure. Ex:
Adenine(A),Guanine(G).
2. Pyrimidine base – single ring structure. Ex:
Cytosine(C),Thymine(T),Uracil(U).

5. Types of nucleotides:
1. Purine(Adenine & Guanine) nucleotide.
2. Pyrimidin(Thymine,Cytosine & Uracil)
nucleotide.

6. Pathways for the biosynthesis of nucleotides: Nucleotide
biosynthesis in the cell can be grouped into two broad classes –
1. De-novo synthesis (synthesis from scratch): It is a biochemical
pathway in which nucleotides are synthesized new from simple
precursor molecules.Such as sugar or amino acids.
2. Salvage pathway ( recycle pathway): This pathway is used to
recover bases and nucleosides formed during the degradation of
RNA and DNA.

8. PURINE SYNTHESIS
De-novo pathway:
ATP GTP
Adenylsuccinate
synthetase
IMP
dehydrogenase
Adenylsuccinate lyase
GMP
synthetase

9. PURINE SYNTHESIS
Salvage pathway :
purine or pyrimidine
bases or nucleosides Nucleotides

10. ANTICANCER DRUGS
Structural analogues purine synthesis inhibitors:
This structural analogues act as competitive
inhibitor of the naturally occurring nucleotides
that are used to synthesized DNA.when wrong
Bases are in corporated the DNA becomes
functionally inactive. There by cell division is
Arrested,so they are useful as anticancer drug.
Example :
Mercaptopurine
Azaserine
Inhibits the conversion of
IMP to GMP & AMP
Glutamine antagonist

11. PYRIMIDINE
BIOSYNTHESIS
De-novo synthesis :
II(CPSII)
3.Aspartate
transcarbamoylase
3’Dihydroorotase
4.Dihydroorotate
dehydrogenase
5.OPRT
6.OMP decarboxylase
6’CTP synthase
7.Ribonucleotide reductase
10.Thymidylate
Synthase,N5,N10 Methyl
THF.
**CAD tri-functional enzyme
**3 rate limiting enzyme
**CPSII most regulated enzyme

12. PYRIMIDINE SYNTHESIS

13. THANK YOU