Difference Between Pyrimidine and Purine

Microbiology is the field where microorganisms are studied scientifically. Whether they are multicellular, acellular or unicellular, all are studied under it. Microbiology is a vast field that encompasses various other subjects under it. It includes protistology, mycology, immunology, virology, bacteriology, and parasitology. Two types of nitrogenases bases which make their compounds in both DNA and RNA i.e. Pyrimidine and Purine, forms the part of Microbiology.  

Pyrimidine vs Purine

The main difference between Pyrimidine and Purine is that Pyrimidine contains two carbon-nitrogen rings and four atoms of Nitrogen. While Purine contains one carbon-nitrogen ring and two atoms of Nitrogen. Pyrimidine has both high boiling and melting point. Whereas Purine has a low melting and boiling point. The melting point of Pyrimidine is 20 to 22 °C. Purine has a melting point of approximately 214 °C. Pyrimidines are smaller in size. While Purines are bigger as compared to Pyrimidine.

Pyrimidine and Purine

Pyrimidine is a heterocyclic organic compound. They are aromatic and are very similar to pyridines. They have wide occurrence in nature. The nomenclature of Pyrimidine is found to be very straight. But like other heterocyclic compounds, it also has some complications, so they exist in the form of amide. The chemical formula of Pyrimidine is C4H4N2. The molar mass of Pyrimidine is 80.088 g mol−1. The melting and boiling point of Pyrimidine are 20 to 22 °C and 123 to 124 °C

Purine is also a heterocyclic aromatic compound, just like Pyrimidine. Purine comes in a wider range of a group called Purines. It contains two carbon-nitrogen rings and two atoms of Nitrogen. Rings in Purine, i.e. Imidazole and Pyrimidine, are fused. Poutine is a bigger compound. It is water-soluble. The chemical formula of Purine is C5H4N4. Purines are generally found in the products that are rich in proteins like in meat products such as kidneys and liver.

Comparison Table Between Pyrimidine and Purine

Parameters of ComparisonPyrimidinePurine
Structure1 hexo-cyclic ring1 pentose and 1 hexose ring
SourceThymine, Cytosine, UracilAdenine and Guanine
SolubilityInsoluble in waterSoluble in water
Boiling Point123 to 124 °C424 °C
Melting Point22°C214 °C
CatabolismCarbon dioxide, beta-amino acids and ammonia.Uric acid

What is Pyrimidine? 

Pyrimidines are an organic cyclic compound and consist of six rings with two atoms of Nitrogen. The structure of Pyrimidine is very much the same as pyridine. Three isomers that have a diazine structure are involved in Pyrimidine to make the nitrogenous base. Nitrogen atoms are found at the position of 1 and 3 in heterocyclic rings. Both in DNA and RNA, Pyradimine is found. There are two nucleobases in DNA made by Pyrimidine, i.e. Cytosine and Thiamine. In RNA, it forms Uracil.

Pyrimidine is insoluble in water. The molecular mass of Pyrimidine is 80.088 g mol−1. Pyrimidines have a very high melting and boiling point as compared to Purines. They are smaller in size. The structure of Pyrimidine includes one hexo-cyclic ring. They can be found in many synthetic compounds like barbiturates and the HIV drug zidovudine. Uric acid and alloxan, derivatives of Pyramidines, were known earlier. But the synthesis was not carried until 1879.

A proper study of Pyramidines began in 1884 by Adolf Pinner, who was a German chemist. The name was also given by Pinner in 1885. Electronic substitution of Pyrimidine is not very easy. Protonation of Pyrimidine also takes place at one time with nitrogen atoms.

What is Purine?

Nucleotide bases found in Purines are adenine and Guanine. These two are considered as the building blocks in RNA and DNA. It is also used to separate deoxyribonucleotides from ribonucleotides. Purines also help in the metabolic and signalling process in the compounds like guanosine monophosphate (GMP) and adenosine monophosphate (AMP). The cellular processes also Purines are needed. When it is formed, they inhibit enzymes that are used to form more purines.

Purines are soluble in water. They are considered as one of the weak bases and acids. If it is dissolved in pure water, then its pH value will be neither acidic nor basic. Purines occur naturally in the form of hypoxanthine, theobromine, caffeine, xanthine, theophylline, uric acid and is guanine. Its functions as biomolecules in other major processes like GTP, cyclic AMP, ATP, NADH, and coenzyme A. It is not found purely in nature. But can be synthesized using organic compounds.

The term ‘Purine’ was used firstly by Emil Fischer in 1884. The first synthesization of Purine took place in 1898. Biologically Purines are synthesized as nucleosides. In meat products, Purines are found in high amounts. In plants, they are found in low amounts. Sources of high Purines include sardines, liver, beef kidneys, sweetbreads, anchovies, brains, scallops, game meats, meat extracts, herring, mackerel, and gravy.

Main Differences Between Pyrimidine and Purine

  1. The structure of Pyrimidine contains 1 hexo-cyclic ring. The structure of Purine contains 1 pentose and 1 hexose ring.
  2. Pyramiodine has a smaller size. Purine has a bigger size.
  3. The source of Pyrimidine is Thymine, Cytosine and Uracil. The source of Purine is Adenine and Guanine.
  4. Pyrimidine is insoluble in water. Purine is soluble in water.
  5. The boiling point of Pyrimidine is. The boiling point of Purine is 
  6. The melting point of Pyrimidine is 22°C. The melting point of Purine is 
  7. Catabolism in Pyrimidine produces Carbon dioxide, beta-amino acids and ammonia. Catabolism in Purine produces Uric acid.
  8. Biosynthesis in Pyrimidine takes place in tissues. Biosynthesis of Purine takes place in the Liver.


Pyrimidine is synthesized by a reaction named Biginelli. Purine is synthesized by a reaction named Traube Purine. Both Pyrimidine and Purine form a nitrogenous base, including the two groups of nucleotide. Cellular processes are performed by both Purine and Pyrimidine. They are required in the same quantities by the cell. Features of Pyrimidine and Purine include activating and self-inhibiting. Self-inhibition activates the formation of Pyrimidine. 

Pyramiding, in turn self-inhibits purine formation. Both act as building blocks that store the genetic information required for the development of cells. Molecules of purines are larger. They are very complex and heavy and are required in greater numbers to participate in a reaction more than Pyrimidine.


  1. https://www.annualreviews.org/doi/abs/10.1146/annurev.arplant.57.032905.105421
  2. https://academic.oup.com/nar/article-abstract/6/9/3073/2359652
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