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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 ...
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.
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]
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.
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. The systematic name of this enzyme class is ATP: d-ribose 5-phosphotransferase. Other names in common use include deoxyribokinase, ribokinase (phosphorylating), and d-ribokinase.
The pathway begins with the conversion of Ribose-5-Phosphate(R5P) to phosphoribosyl pyrophosphate (PRPP) by enzyme ribose-phosphate diphosphokinase (PRPS1). PRPP is then converted to 5-phosphoribosylamine (5-PRA) as glutamine donates an amino group to the C-1 of PRPP.
Phosphoribulokinase (PRK) (EC 2.7.1.19) is an essential photosynthetic enzyme that catalyzes the ATP-dependent phosphorylation of ribulose 5-phosphate (RuP) into ribulose 1,5-bisphosphate (RuBP), both intermediates in the Calvin Cycle. Its main function is to regenerate RuBP, which is the initial substrate and CO 2-acceptor molecule of the ...
Pyruvate, phosphate dikinase, or PPDK (EC 2.7.9.1) is an enzyme in the family of transferases that catalyzes the chemical reaction ATP + pyruvate + phosphate ⇌ {\displaystyle \rightleftharpoons } AMP + phosphoenolpyruvate + diphosphate