Purine Salvage is a biochemical pathway that recycles partially degraded purine bases to reform purine nucleotides.
Purine salvage begins with the free nitrogenous bases, hypoxanthine and guanine. Guanine combines with PRPP to form GMP, whereas Hypoxanthine combines with PRPP to form IMP. IMP can then be interconverted with AMP. Therefore, salvage of AMP occurs through hypoxanthine.
Both salvage reactions with PRPP are catalyzed by HGPRT (hypoxanthine guanine phosphoribosyltransferase). Notably, Lesch-Nyhan Syndrome is caused by a defect of HGPRT and impairs purine salvage.
A less common purine salvage pathway begins with adenine, since adenine is not usually produced by purine degradation. Adenine combines with PRPP to form AMP, in a reaction catalyzed by APRT (adenine phosphoribosyltransferase).
Find Purine Salvage and more Biochemical Pathways among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.