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Purine and pyrimidine are nitrogenous bases that form the nucleotides in RNA and DNA. Purines have two carbon-nitrogen ring bases whereas pyrimidines have one carbon-nitrogen ring base.
Difference Between Purine and Pyrimidine
AREA OF DIFFERENTIATION PURINE PYRIMIDINE
DEFINITION | It is the synthesis of purine nucleotides by the Salvage and De Novo process. | It is the synthesis of pyrimidine nucleotides by the Salvage and De Novo process. |
PATHWAY | The major pathway of synthesis is the Salvage pathway. | The major pathway of synthesis is the De Novo pathway. |
COMPLEXITY | The process of synthesis is relatively complex. | The process of synthesis is similar. |
GLYCINE | Involved. | Not involved. |
SYNTHESIS | Synthesized by Traube Purine synthesis. | Synthesized by Biginelli reaction. |
BOILING POINT | Comparatively high. | Comparatively low. |
MELTING POINT | Comparatively low. | Comparatively low. |
NITROGEN ATOMS | Contains four nitrogen atoms. | Contains two nitrogen atoms. |
CARBON RING | Made up of two carbon rings. | Made up of one carbon ring. |
CATABOLIC PRODUCT | Uric acid is produced as a result of catabolism. | Beta amino acids, carbon dioxide, and ammonia are produced as a result of catabolism. |
Purine
These are compounds that have a six-member carbon ring with two nitrogen atoms. This ring is fused to an imidazole ring. Purines are the most common heterocyclic rings that contain nitrogen in nature. Purines are commonly found in meat products
They are building blocks of genetic material- DNA and RNA. The most basic structure in the biochemistry of purine is the nucleotide which has ribose or deoxyribose, purine base, and a phosphoric base
Adenine, guanine, hypoxanthine, and xanthine are the most important purine bases. The ribosides of these bases occur in metabolism. Free hypoxanthine and xanthine are known to be the intermediates in the degradation of purines. Purines are sparingly soluble in water and body fluids
Solubility of 6.6g/100ml in plasma has been calculated as the maximum solubility by Peter and Van Slyke. They are soluble in the form of uric acid
The other purine bases are caffeine, theobromine, uric acid, and isoguanine
Besides forming nucleic acids, purines also form biomolecules such as ATP, NAD, GTP, cyclic AMP, and coenzyme A. Coenzyme A is involved in the citric acid cycle. ATP is the main energy source of cells. NAD is involved in redox reactions during glycolysis metabolism. Camp-dependent pathways include cyclic AMP as a second messenger during signal transmission
Pyrimidines
These are heterocyclic compounds having six-membered rings and two nitrogen atoms. Their ring structure is similar to that of the purines. There are three isomerising diazene structures included in a nucleobase ring formation. Nitrogen atoms are found in positions one and two in the heterocyclic ring in pyridazine
Pyrimidine has nitrogen atoms on positions one and three in the heterocyclic ring. Pyrimidines undergo synthesis by the process of salvage and de novo
The precursor in the de novo pathway is uridine monophosphate (UMP). This pathway is involved in the process of synthesizing uracil, cytosine, and thymine
On getting catabolised, pyrimidines produce urea, carbon dioxide and water
Synthesis of Purine and Pyrimidine
The synthesis of nucleotides in plants is similar to the synthesis of nucleotides in animals and microorganisms. De Novo and salvage are the two principal pathways of the synthesis of purines and pyrimidines. The de novo pathway builds these nucleotides from scratch by the usage of 5-phosphoribosyl-1-pyrophosphate (PRPP) using carbon dioxide, amino acids, and tetrahydrofolate.
DE NOVO SYNTHESIS- in this, the purine and pyrimidine nucleotides are formed from new and simple precursor molecules.
SALVAGE PATHWAY- in this, this pathway is used for the recovery of nucleotides that are formed at the time of degradation of RNA and DNA.
IMP- inosine monophosphate
AMP- adenosine monophosphate
GMP- guanosine monophosphate
ATP- adenosine triphosphate
GTP- guanosine triphosphate
UMP- uridine monophosphate
UTP- uridine triphosphate
CTP- cytosine triphosphate
Key Difference Between Purine and Pyrimidine
Purines contain two carbon rings and four nitrogen atoms while pyrimidines have a single ring and two atoms of nitrogen
Purines have a high melting point while pyrimidines have low melting points
Purines have a high boiling point while pyrimidines have low boiling points
Purines are formed by Traube purine synthesis while pyrimidines are formed by Vignelli reaction
On catabolism, purines form uric acid while pyrimidine forms beta-amino acids, carbon dioxide, and ammonia
Glycine is involved in the synthesis of purines while glycine is not involved in the synthesis of pyrimidines
Conclusion
The purines and pyrimidine are recurring structures in nucleic acids. They form the basic structure of nucleic acids. The nucleic acids are DNA and RNA which form the genetic material of living organisms. Watson and crick proposed the model in which adenine and guanine (purines) bond with cytosine and thymine (pyrimidines) respectively in DNA. In RNA, thymine is replaced with uracil. De novo and salvage are the two pathways by which pyrimidine and purines are formed.
