Pyrimidine Bases in DNA and RNA

Pyrimidine can be defined as a simple aromatic heterocyclic compound with an organic nature that is quite similar to pyridine. It is known to be one of the three diazines which are six-membered heterocyclics that have two atoms of Nitrogen in the ring. 

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The nitrogen atoms are present in the first and third positions in the ring. Other examples of diazines include pyridazine and pyrazine. In nucleic acids, there are three pyrimidine derivatives known as uracil, thymine, and cytosine. 

Pyrimidine Definition: What does the Term Mean?

According to pyrimidine definition, it is an aromatic compound that consists of nitrogen and carbon atoms that are bonded in a six-membered ring. This term is also used to describe certain derivatives of pyrimidine. These are the three different nitrogenous bases which when added to the two different purines constitute the building blocks for Ribonucleic acid or RNA and Deoxyribonucleic acid or DNA. These nitrogenous bases are created using pyrimidine through a process of adding different functional groups. Thymine, one of the three nitrogenous bases, is seen in the DNA particles. While uracil exists in just the RNA, the third nitrogenous base, cytosine can be found in both RNA and DNA. 

Pyrimidine Structure: What does Pyrimidine look like? 

The basic structure of pyrimidine can be seen as two nitrogen atoms that are bonded with four atoms of carbon. There are atoms of hydrogen which are connected to carbon atoms. Alternating single and double bonds exist between the nitrogen atoms and carbon atoms. Due to this particular bond structure, aromaticity or resonance is created. Hence, the ring created from the bond remains in a stable state. By adding a few more functional groups into the structure, the derivatives of the pyrimidine compound can be obtained. While these derivatives will be contained in the ring, there might be some modifications that can range from the addition of atoms to the creation of complex structures in vitamins and drugs. 

Pyrimidine Uses and Functions of the Derivatives

• The compound pyrimidine as well as the derivatives that it has are quite pervasive in nature. These compounds are present in a variety of amino acids, vitamins, nucleic acids, alkaloids, different toxins, and a plethora of antibiotics. There are so many pyrimidine uses such as the production of proteins and amino acids, contributing to the health of organisms, providing proper and vital nutrients, and improving the immune system in organisms. Pyrimidine and its derivatives also have an important role to play in the antagonizing as well as the destruction of harmful cells. For instance, the neurotoxin named tetrodotoxin is a derivative of pyrimidine. It can be found in different organisms such as the blue-ringed octopus and the pufferfish. The presence of this derivative of pyrimidine can prevent the transmission of different nerve signals which can lead to paralysis and in worse case scenarios, it leads to death. Apart from that, pyrimidine derivatives tend to assist in the development of drugs. These derivatives have always been used in different pharmaceutical companies for creating anti-malaria medications, high blood pressure medications, anti-epilepsy medications, and anesthetics. 

Pyrimidine Synthesis: What is the Process? 

The synthesis of pyrimidine is basically very similar to the process of synthesizing Purines. For the process of synthesizing pyrimidines, there are certain important steps that should be followed. The first step is to synthesize the ring and then it is completely attached to the ribose-phosphate in order to create the pyrimidine nucleotide. These rings of pyrimidine can be assembled from aspartate, ammonia, and bicarbonate. The new pathway for pyrimidine synthesis, also known as pyrimidine biosynthesis, was observed first in certain mutants of the bread mold species Neurospora crassa. The species wasn’t able to synthesize the pyrimidine and hence required both Uracil and cytosine in the growth medium.

Amongst many different pathways used for the synthesis of pyrimidine, one of them is mentioned below. In the case of such pyrimidines, three different nucleotide molecules are present. These molecules are TMP, CMP, and UMP. This particular pathway for the synthesis of pyrimidine can be easily explained with the help of these important steps. 

• The first step in the process of pyrimidine metabolism is to properly synthesize the Carbamoyl Phosphate.

• In the next step, Carbamoyl Aspartate will be synthesized. 

• The process of Ring Closure is performed in order to create dihydroorotate.

• Following the above-mentioned step, the oxidation of dihydroorotate takes place. 

• Ribose Phosphate moiety is added next. 

• The process of DeCarboxylation takes place in order to form UMP

Conclusion

Unlike the Purines that catabolize to the sparingly soluble products such as uric acid, the degradation of pyrimidine involves the process of catabolism to highly water-soluble products. Some of these include CO₂ and NH₃. The process of synthesizing Pyrimidine is very common in order to create medications and other products due to the immune-boosting properties that it has.