Nucleotides are organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common nutrients by the liver.
Uracil is one of the four nucleobases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine (T). Uracil is a demethylated form of thymine.
Uridine (symbol U or Urd) is a glycosylated pyrimidine analog containing uracil attached to a ribose ring (or more specifically, a ribofuranose) via a β-N1-glycosidic bond. The analog is one of the five standard nucleosides which make up nucleic acids, the others being adenosine, thymidine, cytidine and guanosine. The five nucleosides are commonly abbreviated to their symbols, U, A, dT, C, and G, respectively. However, thymidine is more commonly written as 'dT' ('d' represents 'deoxy') as it contains a 2'-deoxyribofuranose moiety rather than the ribofuranose ring found in uridine. This is because thymidine is found in deoxyribonucleic acid (DNA) and usually not in ribonucleic acid (RNA). Conversely, uridine is found in RNA and not DNA. The remaining three nucleosides may be found in both RNA and DNA. In RNA, they would be represented as A, C and G whereas in DNA they would be represented as dA, dC and dG.
A cyclic nucleotide (cNMP) is a single-phosphate nucleotide with a cyclic bond arrangement between the sugar and phosphate groups. Like other nucleotides, cyclic nucleotides are composed of three functional groups: a sugar, a nitrogenous base, and a single phosphate group. As can be seen in the cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) images, the 'cyclic' portion consists of two bonds between the phosphate group and the 3' and 5' hydroxyl groups of the sugar, very often a ribose.
A salvage pathway is a pathway in which a biological product is produced from intermediates in the degradative pathway of its own or a similar substance. The term often refers to nucleotide salvage in particular, in which nucleotides are synthesized from intermediates in their degradative pathway.
Purine nucleoside phosphorylase, PNP, PNPase or inosine phosphorylase is an enzyme that in humans is encoded by the NP gene. It catalyzes the chemical reaction
Nucleic acid metabolism is a collective term that refers to the variety of chemical reactions by which nucleic acids are either synthesized or degraded. Nucleic acids are polymers made up of a variety of monomers called nucleotides. Nucleotide synthesis is an anabolic mechanism generally involving the chemical reaction of phosphate, pentose sugar, and a nitrogenous base. Degradation of nucleic acids is a catabolic reaction and the resulting parts of the nucleotides or nucleobases can be salvaged to recreate new nucleotides. Both synthesis and degradation reactions require multiple enzymes to facilitate the event. Defects or deficiencies in these enzymes can lead to a variety of diseases.
Pyrimidine biosynthesis occurs both in the body and through organic synthesis.
The enzyme pseudouridylate synthase (EC 4.2.1.70) catalyzes the chemical reaction
In enzymology, a nucleoside-diphosphatase (EC 3.6.1.6) is an enzyme that catalyzes the chemical reaction
In enzymology, an uridine nucleosidase (EC 3.2.2.3) is an enzyme that catalyzes the chemical reaction
In enzymology, an alpha,alpha-trehalose phosphorylase is an enzyme that catalyzes the chemical reaction
In enzymology, a deoxyuridine phosphorylase is an enzyme that catalyzes the chemical reaction
In enzymology, a pyrimidine-nucleoside phosphorylase is an enzyme that catalyzes the chemical reaction
In enzymology, a S-methyl-5'-thioadenosine phosphorylase is an enzyme that catalyzes the chemical reaction
Thymidine phosphorylase is an enzyme that is encoded by the TYMP gene and catalyzes the reaction:
In enzymology, a ribose-5-phosphate adenylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, an UDP-N-acetylglucosamine diphosphorylase is an enzyme that catalyzes the chemical reaction
In enzymology, an UTP—hexose-1-phosphate uridylyltransferase is an enzyme that catalyzes the chemical reaction
Uridine phosphorylase 1 is an enzyme that in humans is encoded by the UPP1 gene. It belongs to the uridine phosphorylase enzyme family.
