Adenine

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD medical weight loss NYC and sleep center NYC

Numbered structure of adenine.

Adenine (A, Ade) is a nucleobase classified as a purine derivative, and plays a critical role in numerous biochemical processes. It is a key component of both DNA and RNA, as well as several essential cofactors and cellular energy molecules.

Overview

Adenine is fundamental in cellular respiration, forming part of adenosine triphosphate (ATP), the principal molecule for storing and transferring chemical energy in cells. It is also present in the important cofactors nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD).

In the context of genetic material, adenine is one of the four nucleobases in DNA, where it forms base pairs with thymine through hydrogen bonds. In RNA, adenine pairs with uracil during transcription and protein biosynthesis.

Structure

Adenine is a heterocyclic compound composed of a fused imidazole and pyrimidine ring—together forming the purine structure. It exists in several tautomeric forms, which interconvert rapidly in aqueous solutions. The predominant tautomer under isolated conditions (e.g., in the gas phase or inert matrices) is the 9H-adenine.

Biosynthesis

The biosynthetic pathway of purine metabolism gives rise to adenine and guanine, both synthesized from the common precursor inosine monophosphate (IMP). The purine ring is built stepwise on a ribose phosphate backbone, specifically 5-phosphoribosyl-1-pyrophosphate (PRPP).

Atoms within the adenine ring originate from several sources:

• Glycine
• Glutamine
• Aspartic acid
• Formyl groups carried by tetrahydrofolate

Function

Adenine is essential for the formation of nucleic acids:

• In DNA, it pairs with thymine (A-T) via two hydrogen bonds.
• In RNA, it pairs with uracil (A-U).

Adenine is also involved in the formation of various nucleosides and nucleotides:

• Adenine + ribose → adenosine
• Adenine + deoxyribose → deoxyadenosine
• Adenosine + three phosphate groups → adenosine triphosphate (ATP)

ATP is the primary energy currency of the cell, participating in numerous metabolic pathways. Adenine is also integral to the structure of:

• NAD (nicotinamide adenine dinucleotide)
• FAD (flavin adenine dinucleotide)
• cAMP (cyclic adenosine monophosphate), a second messenger

Base Pairing Diagrams

Adenine-Thymine (DNA)

Adenine-Uracil (RNA)

Adenine-Dihydrouracil (RNA)

Adenine-Pseudouridine (RNA)

History

Adenine was first isolated and named by Albrecht Kossel in 1885, who derived it from the pancreas—hence the name from Greek “aden” (Ἀδήν), meaning “gland.” Historically, adenine was once classified as Vitamin B₄, but this designation is now obsolete.

Notably, adenine forms a structural component of the B-vitamin-derived cofactors:

• Nicotinamide adenine dinucleotide (NAD), from niacin
• Flavin adenine dinucleotide (FAD), from riboflavin

Prebiotic Synthesis

Experiments in the 1960s demonstrated that adenine can be synthesized by heating ammonia with hydrogen cyanide (HCN), suggesting possible relevance to the origin of life on Earth.

In 2011, studies of carbonaceous chondrite meteorites revealed the presence of adenine and other nucleobases, indicating that these biologically relevant molecules may form in outer space and be delivered to early Earth via extraterrestrial means.

See also

• Purine
• Nucleic acid
• DNA replication
• RNA polymerase
• Nucleoside
• Nucleotide
• ATP
• Cofactor (biochemistry)
• Vitamin B complex

External links

• Vitamin B4 MS Spectrum – Golm Metabolome Database

Vitamins A Vitamin A B Biotin Vitamin B1 (see Thiamin) Vitamin B12 Vitamin B6 C Calcium Choline Chromium Copper Vitamin C D Vitamin D

E Energy Drinks Exercise and Athletic Performance Vitamin E F Fluoride Folate I Iodine Iron K Vitamin K

M Magnesium Multivitamin/mineral Supplements N Niacin P Pantothenic Acid Phosphorus Potassium Primary Mitochondrial Disorders R Riboflavin

S Selenium T Thiamin V Vitamin A Vitamin B1 (see Thiamin) Vitamin B12 Vitamin B6 Vitamin C Vitamin D Vitamin E Vitamin K Z Zinc