ribose phosphate diphosphokinase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: D-ribose 5-phosphate + ATP = 5-phospho-alpha-D-ribose 1-diphosphate + AMP + 2 H+. [EC:2.7.6.1, RHEA:15609]

Ribose phosphate diphosphokinase (RPK) activity catalyzes the transfer of a phosphate group from ATP to a ribose-5-phosphate molecule, specifically converting it to 5-phospho-alpha-D-ribose 1-diphosphate (PRPP). This reaction is crucial for the synthesis of purine and pyrimidine nucleotides, which are fundamental building blocks of DNA and RNA.

The enzyme is responsible for the activation of ribose-5-phosphate, making it a suitable substrate for nucleotide biosynthesis. It is involved in multiple metabolic pathways, including the pentose phosphate pathway, purine biosynthesis, and pyrimidine biosynthesis.

Here is a detailed description of the reaction:

* **Substrate:** Ribose-5-phosphate (R5P), an intermediate in the pentose phosphate pathway.
* **Cofactor:** ATP (adenosine triphosphate) provides the phosphate group for the reaction.
* **Product:** 5-phospho-alpha-D-ribose 1-diphosphate (PRPP), an activated form of ribose-5-phosphate.

The reaction proceeds through a two-step mechanism:

1. **Phosphorylation:** RPK transfers the gamma phosphate from ATP to the 5' hydroxyl group of ribose-5-phosphate. This results in the formation of a transient intermediate, which is then converted to PRPP.
2. **Release:** The enzyme releases the product PRPP, which is further utilized in nucleotide biosynthesis.

RPK is a highly conserved enzyme found in all living organisms. Its activity is essential for maintaining nucleotide homeostasis and supporting cellular growth and proliferation. Mutations in RPK can lead to various metabolic disorders, highlighting the vital role of this enzyme in cellular function.'
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Proteins (1)

Compounds (1)