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[1] [2] [3] The vitamins thiamine [4] and cobalamin, [5] and the amino acid tryptophan also contain fragments derived from PRPP. [6] It is formed from ribose 5-phosphate (R5P) by the enzyme ribose-phosphate diphosphokinase: [7] It plays a role in transferring phospho-ribose groups in several reactions, some of which are salvage pathways: [8]
The enzyme is involved in the synthesis of nucleotides (purines and pyrimidines), cofactors NAD and NADP, and amino acids histidine and tryptophan, [1] [2] [3] linking these biosynthetic processes to the pentose phosphate pathway, from which the substrate ribose 5-phosphate is derived. Ribose 5-phosphate is produced by the pentose phosphate ...
Ribose 5-phosphate (R5P) is both a product and an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the production of ribulose 5-phosphate. Depending on the body's state, ribulose 5-phosphate can reversibly isomerize to ribose 5-phosphate.
A key regulatory step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate by ribose-phosphate diphosphokinase, which is activated by inorganic phosphate and inactivated by purine ribonucleotides. It is not the committed step to purine synthesis because PRPP is also used in pyrimidine synthesis and salvage pathways.
Amidophosphoribosyltransferase (ATase), also known as glutamine phosphoribosylpyrophosphate amidotransferase (GPAT), is an enzyme responsible for catalyzing the conversion of 5-phosphoribosyl-1-pyrophosphate (PRPP) into 5-phosphoribosyl-1-amine (PRA), using the amine group from a glutamine side-chain.
Histidine is synthesized from phosphoribosyl pyrophosphate (PRPP), which is made from ribose-5-phosphate by ribose-phosphate diphosphokinase in the pentose phosphate pathway. The first reaction of histidine biosynthesis is the condensation of PRPP and adenosine triphosphate (ATP) by the enzyme ATP-phosphoribosyl transferase.
D-Ribose pyranase is an enzyme that catalyzes the interconversion of β-D-ribopyranose and β-D-ribofuranose. [1] This enzyme is an isomerase that has only been found in bacteria and viruses . It has two known functions of helping transport ribose into cells and producing β- D -ribofuranose, which can later be used to make ribose 5-phosphate ...
IMP is synthesized de novo from glucose through the pentose phosphate pathway which produces ribose 5-P, which then converts to PRPP that with the amino acids glycine, glutamine, and aspartate (see Purine metabolism) can be further converted into IMP. [7]