Purine and Pyrimidine Bases in DNA and RNA

In this purine and pyrimidine bases in DNA and RNA post we have briefly explained about molecular composition of nucleotides, purine bases, minor purine and pyrimidine base. Read on to learn more about purine and pyrimidine base!

Nucleotides are the building blocks of nucleic acids, including deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The storage and transmission of genetic information is dealt with by nucleic acids. A nucleotide derivative is the universal currency of energy, ATP. Important co-enzymes like NAD+ and FAD, as well as metabolic regulators like cAMP and cGMP, are made up of nucleotides.

Purine and Pyrimidine Base

Nitrogenous base, (purine and pyrimidine base), Pentose sugar, either ribose or deoxyribose; Phosphate groups esterified to the sugar. A nucleotide or nucleoside mono-phosphate is formed when a nucleoside is esterified to a phosphate group. 

A nucleoside diphosphate is formed when a second phosphate is esterified to the existing phosphate group. A nucleoside triphosphate is formed when a third phosphate group is attached to a nucleoside. Nucleic acids (DNA and RNA) are nucleoside monophosphate polymers. Two important types of nitrogenous bases; the purine and pyrimidine base are present in nucleic acids.

Purine Bases

Adenine and guanine are the purines found in both RNA and DNA. Guanine is a 2-amino, 6-oxypurine, while adenine is a 6-amino purine. Figure shows the purine ring numbering in relation to the adenine and guanine structures.

Purine and Pyrimidine Bases

Purine Bases

Minor Purine Bases

These bases are called minor bases because they are found in modest concentrations in nucleic acids. Hypoxanthine (6-oxopurine) and xanthine are the two (2, 6-di-oxopurine).

The degradation of other purines results in the formation of uric acid (2,6,8-tri-oxopurine). It can be found in both “enol” and “keto” forms (tautomeric forms). Under physiological settings, the keto form is by far the most common.

Purine and Pyrimidine Bases

Minor Purine Bases

Pyrimidine Bases

Cytosine, thymine, and uracil are the pyrimidines found in nucleic acids. Cytosine can be found in DNA and RNA. Thymine is found in DNA, while uracil is found in RNA. Some kinds of RNA contain a few more modified pyrimidine bases, such as dihydrouracil and 5-methyl cytosine.

Purine and Pyrimidine Bases

Pyrimidine Bases

Further Readings

Reference