Which enzyme is involved in the salvage pathway of purine metabolism, specifically Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT), Phosphoribosyl Pyrophosphate (PRPP) synthetase, Adenosine Deaminase, or Xanthine Oxidase?

From the Guidelines

The enzyme involved in the salvage pathway of purine metabolism is HGPRT (Hypoxanthine-guanine phosphoribosyltransferase). HGPRT plays a crucial role in recycling purine bases by catalyzing the conversion of hypoxanthine and guanine to their respective nucleotides, IMP and GMP, using phosphoribosyl pyrophosphate (PRPP) as a co-substrate, as seen in the metabolism of azathioprine 1. This salvage pathway is metabolically efficient as it allows cells to reuse purine bases rather than synthesizing them de novo, which requires more energy. HGPRT deficiency leads to Lesch-Nyhan syndrome, characterized by hyperuricemia, neurological problems, and self-mutilating behavior, highlighting the importance of this enzyme in normal purine metabolism 1. While PRPP synthetase provides the PRPP substrate, adenosine deaminase converts adenosine to inosine, and xanthine oxidase is involved in purine degradation to uric acid, none of these enzymes directly function in the purine salvage pathway like HGPRT does. Key points to consider include:

• HGPRT is essential for the salvage pathway of purine metabolism
• Deficiency in HGPRT leads to severe clinical manifestations
• Other enzymes like PRPP synthetase, adenosine deaminase, and xanthine oxidase have different roles in purine metabolism.

From the Research

Enzyme Involved in Purine Salvage Pathway

The enzyme involved in the salvage pathway of purine metabolism is:

• Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) 2, 3, 4, 5, 6

Role of HGPRT in Purine Metabolism

HGPRT plays a key role in the purine salvage pathway, which is essential for the recycling of purine bases and the maintenance of purine nucleotide pools 3, 6.

Relationship Between HGPRT and Other Enzymes

Other enzymes mentioned, such as adenosine deaminase, PRPP synthetase, and xanthine oxidase, are also involved in purine metabolism, but they are not directly involved in the salvage pathway 5.

Importance of HGPRT in Neuronal Differentiation

HGPRT is particularly important in neuronal differentiation, and its deficiency can lead to disorders such as Lesch-Nyhan disease 2, 6.