Difference Between Adenine and Adenosine

Adenine and adenosine
The terms 'adenine' and 'adenosine' are often used interchangeably, to refer to each other, however they differ with respect to their chemical structure and the other biomolecules that they interact with. We compare these molecules and elucidates the difference between them.
Did You Know?
Joan OrĂ³, a Spanish biochemist, was awarded the Oparin Medal in 1986, for the prebiotic synthesis of adenine from an aqueous solution of hydrogen cyanide.
Adenine and adenosine, both are important biomolecules that not only occur in nucleic acids but also play a role in many other cellular processes by conjugating themselves with other biomolecules. They primarily function as one of the building blocks required for the synthesis of DNA and RNA molecules. They are often mistaken for each other due to their similar primary function, however they have different compositions and secondary functions.

To understand the distinct difference between these two molecules. One must first acquaint themselves with terms such as nucleobase, nucleoside, and nucleotide. All these terms refer to the various forms in which the DNA and RNA components occur in a cell. Nucleobases are nitrogen-containing aromatic compounds that are the basic building blocks of both nucleic acids. When a ribose sugar molecule is added to a nucleobase, it forms a nucleoside. The addition of phosphate groups to a nucleoside, yields a nucleotide.
Adenine molecule formula
It is a purine nucleobase with the molecular formula C5H5N5. Its IUPAC name is 9H-purin-6-amine, but is also known as 6-aminopurine. It consists of a heterocyclic structure, with a imidazole ring attached to a pyrimidine ring. It exhibits the presence of an additional amine group at the 6th carbon. It acts as a core molecule in a number of coenzymes. It conjugates and bonds with a pentose sugar molecule to form a nucleoside, adenosine.
The pentose sugar is ribose in the case of RNA, and it is deoxygenated ribose or deoxyribose in DNA. In DNA, adenine binds to thymine, whereas it binds to uracil in RNA. The nucleoside form of this molecule interacts with a variety of other biomolecules for the proper functioning of cellular processes.
Adenosine molecule formula
It is a purine nucleoside, consisting of an adenine molecule attached to a ribose sugar via a glycosidic bond. Its molecular formula is C10H13N5O4. Its IUPAC name is (2R,3R,4S,5R)-2-(6-aminopurin-9-yl)-5-(hydroxymethyl)oxolane-3,4-diol. It forms a nucleotide of DNA and RNA by the formation of phosphodiester bonds between phosphate groups of adjacent bases.
In additions to this it has been observed to function as an analgesic, a vasodilator, and an anti-arrhythmia agents. This molecule is of pharmacological importance due to these functions, as well as the fact that it is a naturally synthesized molecule in all the cells of the organism. Its nucleotide occurs in four forms - adenosine monophosphate (AMP), cyclic AMP (cAMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP).
Major Difference
The major differentiating factor between these two molecules is the fact that adenine is the basic nucleobase, which when bonded to a pentose sugar like ribose, yields adenosine, which is a nucleoside. In other words, adenosine is a complex molecule, where adenine is one of the components. Hence adenosine is a bigger molecule, and is functionally more active.
Role and Function in Biological Systems
Adenine binds to thymine (in DNA) and uracil molecules (in RNA) with the help of two hydrogen bonds, thereby helping in stabilizing the nucleic acid structure. It was previously included in the group of B-complex vitamins, however it is now excluded as it is not a true vitamin. However, it form conjugates with other vitamins like niacin and folic acid to form cofactors and coenzymes that regulate metabolic pathways.
Adenosine, along with its receptors regulate the cell cycle progression, and the passage of molecules across the blood-brain barrier. Its phosphate forms play a role in various metabolic pathways for the yield of energy, which is in the form of ATP. It has also been observed to function as a neurotransmitter and an anti-inflammatory agent.
Adenine is the basic functional molecule, which when conjugated with other functional groups, yields complex molecules like adenosine and its phosphate forms, that are involved in various cellular processes. Both these molecules are vital for the proper functioning of an organisms physiological processes.