Nucleosides & Nucleotides
Nucleosides & Nucleotides
Nucleosides are the structural subunit of nucleic acids such as DNA and RNA. A nucleoside, composed of a nucleobase, is either a pyrimidine (cytosine, thymine or uracil) or a purine (adenine or guanine), a five carbon sugar which is either ribose or deoxyribose. Nucleosides play an essential role in intermediary metabolism, biosynthesis of macromolecules and cell signaling through interaction with purinergic receptors. In medicinal field, several nucleosides are used as antiviral or anticancer agents. Several new nucleosides are showing high degree of potency and selectivity against the herpes group of viruses. Nucleosides are responsible for encoding, transmitting and expressing genetic information in all living things.
Nucleotides are building blocks of nucleic acids DNA and RNA. Nucleotides are composed of a nitrogenous base, a five-carbon sugar (ribose or deoxyribose), and at least one phosphate group. Thus a nucleoside plus a phosphate group yields a nucleotide. The components used in de novo nucleotide synthesis are derived from biosynthetic precursors of carbohydrate and amino acid metabolism, and from ammonia and carbon dioxide. Nucleoside triphosphates (ATP, GTP, CTP and UTP), play a central role in cell metabolism. Malfunctioning nucleotides are one of the main causes of all cancers known of today.
Several nucleotide and nucleoside analogues inhibit the reverese-trancriptase, an enzyme that controls the replication of the genetic material of the human immunodeficiency virus (HIV) and other retroviruses.
