Purines - basics and synthesis

1. Purine- Basics and Synthesis
Varinder Khepar
PhD Chemistry
1

2. 2

3. Nucleic Acid Building Blocks
• Nucleic acids are polymers that consist of
nucleotide residues. DNA and RNA are
polymers of nucleotide units.
• Each nucleotide is put together from three
building blocks:
1. phosphoric acid
2. a monosaccharide
3. an organic base
3

4. 1) Phosphoric Acid
4

5. 2. Monosaccharides
• All nucleotides are constructed from one of
these two monosaccharides:
5

6. 3) Organic Bases
• There are two types of organic bases (amines)
that are incorporated into nucleic acids:
a) purines
b) pyrimidines
6

7. 7

8. Purines
• Purine is a heterocyclic aromatic organic
compound composed of a pyrimidine ring
fused with imidazole ring.
• It consists of two hydrogen-carbon rings and
four nitrogen atoms
8

9. • Purine is both a very weak acid and an even
weaker base
• It is water-soluble
• It comprises adenine and guanine as
nucleobases.
• The melting point of purine is 214 °c
• Catabolism results in the production of uric
acid
9

10. Occurrence of purines
• Found in high concentration in meat and meat
products, especially internal organs such
as liver and kidney
• Plant-based diets are low in purines
• Moderate amount of purine is also contained
in fish, seafood, mushrooms, green peas,
dried peas and beans.
10

11. Notable purines
• There are many naturally occurring purines. They
include the nucleobases adenine and guanine .
• In DNA, these bases form hydrogen bonds with
their complementary pyrimidines, thymine and c
ytosine, respectively.
• In RNA, the complement of adenine
is uracil instead of thymine.
• Other notable purines
are hypoxanthine (4), xanthine (5) and uric acid.
11

12. 12

13. History of purine
• The word purine (pure urine) was coined by
the German chemist Emil Fischer in 1884.
• He synthesized it for the first time in 1898.
• The starting material for the reaction
sequence was uric acid (8), which had been
isolated from kidney stones.
13

14. • Uric acid (8) was reacted with PCl5 to give
2,6,8-trichloropurine (10), which was
converted with HI and PH4I to give 2,6-
diiodopurine (11). The product was reduced to
purine (1) using zinc dust.
14

15. Synthesis of purine
• Laboratory synthesis
• Purine is obtained in good yield when formamide is heated
in an open vessel at 170 °C for 28 hours.
15

16. Synthesis of Purine derivatives
• Four molecules of HCN tetramerize to
form diaminomaleodinitrile (12)
• Five molecules of HCN condense in an
exothermic reaction to make adenine
16

17. 17

18. Traube purine synthesis (in 1900)
18

19. Refrences
• http://www.sivabio.50webs.com/nucleicacid.
htm
• Fasullo, M., & Endres, L. (2015). Nucleotide
Salvage Deficiencies, DNA Damage and
Neurodegeneration. Int. J. Mol. Sci., 16(12),
9431–9449. doi:10.3390/ijms16059431.
• https://byjus.com/biology/difference-
between-purines-and-pyrimidines/
• https://en.wikipedia.org/wiki/Purine
19

20. THANK YOU
20