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Nucleotides are organic chemical compounds from the group of phosphate esters. They are esters of nucleosides and phosphoric acid (nucleoside 5′-phosphates).
What is a nucleotide?
Nucleotide is the basic unit (monomer) that builds nucleic acids. Due to the type of pentosis, it stands out two types of nucleotides: ribonucleotides (containing ribose) i deoxyribonucleotides (containing deoxyribose). Depending on the type of nitrogen base, they have been divided into 5 types: adenosine-5′-monophosphate, guanosine-5′-monophosphate, cytidine-5′-monophosphate, thymidine-5′-monophosphate, uridine-5′-monophosphate.
Nucleotides – properties
Nucleotides are the basic components of nucleic acids (DNA and RNA). In the cell, they play a significant role in the processes of metabolism and signal transmission. ATP (adenosine triphosphate) and GTP (guanosine triphosphate) are the main source of energy necessary for many chemical reactions taking place in cells, and cyclic adenosine monophosphate and cyclic guanosine monophosphate participate in signaling pathways and are co-factors for enzymes (e.g. NAD +, FMN, A) and coenzymes.
Functions of selected nucleotides
Adenozyno-5′-diphosphoran, ADP – an organic chemical compound composed of ribose, adenine and two phosphate groups. It is formed from ATP by hydrolysis or the transfer of one phosphorus residue from ATP to an acceptor (for example, glucose or protein). After attaching one phosphate group, ATP is formed from it with the formation of a high-energy anhydride bond.
Adenozyno-5′-monophosphorane (adenosine monophosphate, AMP) – a ribonucleotide resulting from the attachment of a phosphate residue to the 5 ‘carbon of adenosine; can be converted to IMP by AMP deaminase with simultaneous release of ammonia. As a result of metabolism, adenosine monophosphate can be converted into uric acid, which is then excreted from the body.
Dinukleotyd flawinoadeninowy (FAD – oxidized form, FADH2 – reduced form) – an organic chemical compound composed of flavin mononucleotide (FMN) (riboflavin derivative) and adenosine monophosphate (AMP). Oxidoreductase coenzyme acting as a carrier of electrons and protons (hydrogen cations). It transfers two protons and two electrons, as a result of which the oxidized form of FAD reversibly changes into the reduced form of FADH2.
DNA nucleotide
Nucleic acids store the organism’s genetic information and mediate the production of proteins according to the rules of the genetic code. Nucleic acid monomer – nucleotide – consists of a nucleoside, i.e. a pentose molecule (for ribose RNA, for deoxyribose DNA), to which it is attached at the first carbon atom, an N-glycosidic bond, a nitrogen base (purine or pyrimidine), and a phosphate residue, attached to the third and the fifth carbon atom of two adjacent polymer pentoses. So between nucleotides there is a phosphodiester bond. The bases are adenine, guanine, cytosine, and uracil (in RNA) or thymine (in DNA). Nitrogen bases are characterized by the ability to form pairs, but there is a strictly defined rule: adenine always combines with thymine, and guanine with cytosine. This feature is called complementarity of nitrogen bases.