Topic overview

Start with the big picture

De novo purine synthesis begins with PRPP, an activated ribose donor, and builds the purine ring to form IMP. The pathway requires energy and folate-derived one-carbon units, and its rate-limiting step is regulated by PRPP and purine end products. IMP branches into AMP and GMP synthesis, with reciprocal ATP and GTP requirements helping balance their pools. Salvage enzymes HGPRT and APRT recycle hypoxanthine, guanine, and adenine, conserving energy and PRPP. The pathway also connects to clinical conditions: HGPRT deficiency is associated with Lesch–Nyhan syndrome, while ADA deficiency can cause SCID. Purine degradation produces uric acid, and xanthine oxidase inhibitors reduce its formation.