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.
Deoxyribose, or more precisely 2-deoxyribose, is a monosaccharide with idealized formula H−(C=O)−(CH2)−(CHOH)3−H. Its name indicates that it is a deoxy sugar, meaning that it is derived from the sugar ribose by loss of a hydroxy group. Discovered in 1929 by Phoebus Levene, deoxyribose is most notable for its presence in DNA. Since the pentose sugars arabinose and ribose only differ by the stereochemistry at C2′, 2-deoxyribose and 2-deoxyarabinose are equivalent, although the latter term is rarely used because ribose, not arabinose, is the precursor to deoxyribose.
Guanosine-5'-triphosphate (GTP) is a purine nucleoside triphosphate. It is one of the building blocks needed for the synthesis of RNA during the transcription process. Its structure is similar to that of the guanosine nucleoside, the only difference being that nucleotides like GTP have phosphates on their ribose sugar. GTP has the guanine nucleobase attached to the 1' carbon of the ribose and it has the triphosphate moiety attached to ribose's 5' carbon.
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.
A nucleoside triphosphate is a nucleoside containing a nitrogenous base bound to a 5-carbon sugar, with three phosphate groups bound to the sugar. They are the molecular precursors of both DNA and RNA, which are chains of nucleotides made through the processes of DNA replication and transcription. Nucleoside triphosphates also serve as a source of energy for cellular reactions and are involved in signalling pathways.
Cytidine monophosphate, also known as 5'-cytidylic acid or simply cytidylate, and abbreviated CMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside cytidine. CMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase cytosine; hence, a ribonucleoside monophosphate. As a substituent it takes the form of the prefix cytidylyl-.
Apyrase is a calcium-activated plasma membrane-bound enzyme that catalyses the hydrolysis of ATP to yield AMP and inorganic phosphate. Two isoenzymes are found in commercial preparations from S. tuberosum. One with a higher ratio of substrate selectivity for ATP:ADP and another with no selectivity.
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.
Ribose-phosphate diphosphokinase is an enzyme that converts ribose 5-phosphate into phosphoribosyl pyrophosphate (PRPP). It is classified under EC 2.7.6.1.
In enzymology, a phosphopentomutase is an enzyme that catalyzes the chemical reaction
In enzymology, a S-methyl-5-thioribose-1-phosphate isomerase is an enzyme that catalyzes the chemical reaction
ADP-ribose diphosphatase (EC 3.6.1.13) is an enzyme that catalyzes a hydrolysis reaction in which water nucleophilically attacks ADP-ribose to produce AMP and D-ribose 5-phosphate. Enzyme hydrolysis occurs by the breakage of a phosphoanhydride bond and is dependent on Mg2+ ions that are held in complex by the enzyme.
In enzymology, a guanosine-5'-triphosphate,3'-diphosphate diphosphatase (EC 3.6.1.40) is an enzyme that 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 ATP phosphoribosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, an uridine phosphorylase is an enzyme that catalyzes the chemical reaction
Decaprenyl-phosphate phosphoribosyltransferase is an enzyme with systematic name trans,octacis-decaprenylphospho-beta-D-ribofuranose 5-phosphate:diphosphate phospho-alpha-D-ribosyltransferase. This enzyme catalyses the following chemical reaction
Alpha-D-ribose 1-methylphosphonate 5-triphosphate synthase is an enzyme with systematic name ATP:methylphosphonate 5-triphosphoribosyltransferase. This enzyme catalyses the following chemical reaction
Mn2+-dependent ADP-ribose/CDP-alcohol diphosphatase (EC 3.6.1.53, Mn2+-dependent ADP-ribose/CDP-alcohol pyrophosphatase, ADPRibase-Mn) is an enzyme with systematic name CDP-choline phosphohydrolase. This enzyme catalyses the following chemical reaction
UDP-2,3-diacylglucosamine diphosphatase (EC 3.6.1.54, UDP-2,3-diacylglucosamine hydrolase, UDP-2,3-diacylglucosamine pyrophosphatase, ybbF (gene), lpxH (gene)) is an enzyme with systematic name UDP-2,3-bis((3R)-3-hydroxymyristoyl)-alpha-D-glucosamine 2,3-bis((3R)-3-hydroxymyristoyl)-beta-D-glucosaminyl 1-phosphate phosphohydrolase. This enzyme catalyses the following chemical reaction
