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Ribose-phosphate diphosphokinase requires Mg 2+ for activity; the enzyme acts only on ATP coordinated with Mg 2+. Ribose-phosphate diphosphokinase is regulated by phosphorylation and allostery. It is activated by phosphate and inhibited by ADP; it is suggested that phosphate and ADP compete for the same regulatory site. At normal concentrations ...
In enzymology, a ribokinase (EC 2.7.1.15) is an enzyme that catalyzes the chemical reaction. ATP + d-ribose ⇌ ADP + d-ribose 5-phosphate Thus, the two substrates of this enzyme are ATP and d-ribose, whereas its two products are ADP and d-ribose 5-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.
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.
In enzymology, a phosphoribokinase (EC 2.7.1.18) is an enzyme that catalyzes the chemical reaction. ATP + D-ribose 5-phosphate ADP + D-ribose 1,5-bisphosphate. Thus, the two substrates of this enzyme are ATP and D-ribose 5-phosphate, whereas its two products are ADP and D-ribose 1,5-bisphosphate.
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 ).
The general structure of a ribonucleotide consists of a phosphate group, a ribose sugar group, and a nucleobase, in which the nucleobase can either be adenine, guanine, cytosine, or uracil. Without the phosphate group, the composition of the nucleobase and sugar is known as a nucleoside.