The pentose phosphate pathway (PPP) is a crucial metabolic route parallel to glycolysis, primarily responsible for producing NADPH and pentose sugars. One of its vital roles is providing precursors for nucleotide biosynthesis, essential for DNA and RNA synthesis. Among the metabolites generated, one stands out as the common precursor for both purine and pyrimidine nucleotide biosynthesis.

This article explains the key metabolite derived from the pentose phosphate pathway that serves as the foundation for nucleotide synthesis.

Pentose Phosphate Pathway and Its Products

The PPP consists of two phases:

• Oxidative phase: Generates NADPH and ribulose-5-phosphate.

• Non-oxidative phase: Converts ribulose-5-phosphate into ribose-5-phosphate and other sugar phosphates.

The ribose-5-phosphate (R5P) produced is a five-carbon sugar critical for nucleotide synthesis.

Role of PRPP in Nucleotide Biosynthesis

• Ribose-5-phosphate is converted into phosphoribosyl pyrophosphate (PRPP) by the enzyme PRPP synthetase.

• PRPP is an activated ribose sugar donor, serving as the common substrate for the synthesis of purine and pyrimidine nucleotides.

• It provides the ribose-phosphate backbone onto which nitrogenous bases are attached during nucleotide assembly.

Why PRPP is the Key Metabolite

• PRPP acts as a metabolic hub linking carbohydrate metabolism (via PPP) to nucleotide biosynthesis.

• It is essential for the formation of nucleotides, nucleic acids, and other important biomolecules like NAD and coenzyme A.

• Defects in PRPP synthetase or its regulation can lead to metabolic disorders involving nucleotide imbalance.

Evaluating the Given Options

Conclusion

The common metabolite derived from the pentose phosphate pathway that serves as a precursor in nucleotide biosynthesis is PRPP (phosphoribosyl pyrophosphate).

Correct answer: (1) PRPP