Ribose-5-phosphate pyrophosphokinase

The final control mechanism is the inhibition of PRPP synthesis by the allosteric regulation of ribose phosphate pyrophosphokinase. This enzyme is inhibited... 

PRPP is an "activated pentose" that participates in the synthesis of purines and pyrimidines, and in the salvage of purine bases (see p. 294). Synthesis of PRPP from ATP and ribose 5-phosphate is catalyzed by PRPP synthetase (ribose phosphate pyrophosphokinase, Figure 22.6). This enzyme is activated by inorganic phosphate (Pi) and inhibited by purine nucleotides (end-product inhibition). [Note The sugar moiety of PRPP is ribose, and therefore ribonucleotides are the end products of de novo purine synthesis. When deoxy-ribonucleotides are required for DNA synthesis, the ribose sugar moiety is reduced (see p. 295).]... 

V The prs gene (coding for ribose phosphate pyrophosphokinase ) was isolated and integrated into the chromosome... 

Ribose phosphate pyrophosphokinase catalyzes the phosphorylation of ribose-5-phosphate to give PRPP. 

Purine metabolism Ribose phosphate pyrophosphokinase Ph 0 sph oribo syl-glycineamide synthetase Xanthine oxidase... 

The formation of PP-ribose-P is catalyzed by the enzyme, ribose phosphate pyrophosphokinase ... 

Ribose phosphate pyrophosphokinase from tumor cells is inhibited by excess ATP, ADP, CTP, and other triphosphates, all of which are competitive with respect to MgATP inhibition by MgGTP is not competitive (40). The erythrocyte enzyme is inhibited by ADP, and this is relieved by increased phosphate increased ATP has no effect. GDP also inhibits, but this is not affected by phosphate 2,3-diphosphoglycerate is also a potent... 

The formation of PRPP from ribose-5-phosphate and ATP is catalyzed by ribose-5-phosphate pyrophosphokinase (fig. 23.7). This is an unusual kinase because the pyrophos-phoryl group is transferred rather than the phosphoryl group. 

PURINE NUCLEOTIDES The de novo synthesis of purine nucleotides begins with the formation of 5-phospho-a-D-ribosyl- 1-pyrophosphate (PRPP) catalyzed by ribose-5-phosphate pyrophosphokinase (PRPP synthetase). 

Phosphoribosyl-l-Ribose-5 Phosphate Pyrophospate Pyrophosphokinase (PRPP)... 

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