Purine phosphoribosyltransferase (PRTase)

Phosphoribosyltransferase (PRTase) enzymes in the purine salvage pathway, primarily including hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and adenine phosphoribosyltransferase (APRT), are essential for recycling purine bases into nucleotides [StatPearls, Biochemistry, Purine Metabolism]. These enzymes catalyze the transfer of a 5-phosphoribosyl group from phosphoribosyl pyrophosphate (PRPP) to hypoxanthine, guanine, or adenine to form IMP, GMP, or AMP, respectively [UniProt, HPRT1]. This pathway is crucial for maintaining the nucleotide pool, especially in the brain, which has limited de novo synthesis capacity [NIH, Lesch-Nyhan Syndrome]. In pharmacology, HGPRT is the key enzyme responsible for the metabolic activation of thiopurine prodrugs such as 6-mercaptopurine and azathioprine into their active, cytotoxic nucleotide forms used in oncology and immunology [PubMed, Thiopurine Metabolism]. Conversely, genetic deficiency of HGPRT leads to Lesch-Nyhan syndrome, characterized by severe gout and neurological symptoms, while APRT deficiency causes 2,8-dihydroxyadenine urolithiasis [NCBI, Purine Metabolism Disorders]. Furthermore, these enzymes are significant targets for anti-parasitic drug development, as many protozoa lack de novo pathways and rely entirely on salvage for survival [Journal of Medicinal Chemistry, Targeting Parasitic PRTases].

Other names

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)Adenine phosphoribosyltransferase (APRT)HPRT1APRTPurine salvage pathway enzymes

Metabolic activation of antimetabolite prodrugs into cytotoxic nucleotides and competitive inhibition of purine recycling in parasites.