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.
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.
GTP cyclohydrolase I (GTPCH) (EC 3.5.4.16) is a member of the GTP cyclohydrolase family of enzymes. GTPCH is part of the folate and biopterin biosynthesis pathways. It is responsible for the hydrolysis of guanosine triphosphate (GTP) to form 7,8-dihydroneopterin triphosphate (7,8-DHNP-3'-TP, 7,8-NH2-3'-TP).
GTP cyclohydrolases are enzymes that catalyze imidazole ring opening of guanosine triphosphate (GTP). This reaction is the committed step in the biosynthesis of multiple coenzymes, tRNA bases, and the phytotoxin toxoflavin. Several GTP cyclohydrolases exist, which sometimes synthesize different products for different pruposes:
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.
In enzymology, an acid—CoA ligase (GDP-forming) is an enzyme that catalyzes the chemical reaction
In enzymology, a succinate—CoA ligase (GDP-forming) is an enzyme that catalyzes the chemical reaction
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
The enzyme guanosine-3′,5′-bis(diphosphate) 3′-diphosphatase (EC 3.1.7.2) catalyzes the reaction
In enzymology, a diaminohydroxyphosphoribosylaminopyrimidine deaminase (EC 3.5.4.26) is an enzyme that catalyzes the chemical reaction
In enzymology, a GTP cyclohydrolase IIa (EC 3.5.4.29) is an enzyme that catalyzes the chemical reaction
In enzymology, a phosphoribosyl-AMP cyclohydrolase (EC 3.5.4.19) is an enzyme that catalyzes the chemical reaction
In enzymology, a GTP diphosphokinase is an enzyme that catalyzes the chemical reaction
In enzymology, a guanosine-triphosphate guanylyltransferase (EC 2.7.7.45) is an enzyme that catalyzes the chemical reaction
In enzymology, a mannose-1-phosphate guanylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a nucleoside-triphosphate-adenylate kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a nucleoside-triphosphate-aldose-1-phosphate nucleotidyltransferase is an enzyme that catalyzes the chemical reaction
2-amino-5-formylamino-6-ribosylaminopyrimidin-4(3H)-one 5'-monophosphate deformylase (EC 3.5.1.102, ArfB) is an enzyme with systematic name 2-amino-5-formylamino-6-(5-phospho-D-ribosylamino)pyrimidin-4(3H)-one amidohydrolase. This enzyme catalyses the following chemical reaction
2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)pyrimidine is a metabolite in the purine metabolism, formed by the hydrolysis of GTP by GTP cyclohydrolase II. Alternatively two separate enzymes can carry out this reaction, initially GTP cyclohydrolase IIa hydrolyses the 8,9 bond to form 2-Amino-5-formylamino-6-(5-phospho-D-ribosylamino)pyrimidin-4(3H)-one, followed by de-formylation by 2-amino-5-formylamino-6-ribosylaminopyrimidin-4(3H)-one 5'-monophosphate deformylase. 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)pyrimidine is deaminated by Diaminohydroxyphosphoribosylaminopyrimidine deaminase to form 5-amino-6-(5-phosphoribosylamino)uracil.
