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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.
Ribose-5-phosphate isomerase (Rpi) encoded by the RPIA gene is an enzyme (EC 5.3.1.6) that catalyzes the conversion between ribose-5-phosphate (R5P) and ribulose-5-phosphate (Ru5P). It is a member of a larger class of isomerases which catalyze the interconversion of chemical isomers (in this case structural isomers of pentose ).
Ribose-5-phosphate isomerase deficiency (RPID) is a rare human disorder caused by mutations in ribose-5-phosphate isomerase, an enzyme of the pentose phosphate pathway.With only four known cases – all diagnosed between 1984 and 2019 – RPI deficiency is the second rarest disease, with Fields condition being the rarest, affecting two known individuals, Catherine and Kirstie Fields.
The pentose phosphate pathway. The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt or HMP shunt) is a metabolic pathway parallel to glycolysis. [1] It generates NADPH and pentoses (five-carbon sugars) as well as ribose 5-phosphate, a precursor for the synthesis of nucleotides. [1]
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.
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 ...
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 Mg 2+ ions that are held in complex by the enzyme.
Ribose is a constituent of RNA, and the related molecule, deoxyribose, is a constituent of DNA. Phosphorylated pentoses are important products of the pentose phosphate pathway , most importantly ribose 5-phosphate (R5P), which is used in the synthesis of nucleotides and nucleic acids , and erythrose 4-phosphate (E4P), which is used in the ...