Purines

Purines - basics and synthesis

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

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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: phosphoric acid a monosaccharide 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: purines pyrimidines 6

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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 cytosine, respectively. In  RNA, the complement of adenine is  uracil  instead of thymine . Other notable purines are hypoxanthine ( 4 ),  xanthine  ( 5 ) and  uric acid. 11

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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 PCl 5  to give 2,6,8-trichloropurine ( 10 ), which was converted with  HI and  PH 4 I 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

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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