Final answer:
HPRT is an enzyme in the purine salvage pathway that converts guanine to GMP and hypoxanthine to IMP; it's crucial for cells lacking de novo synthesis and its deficiency causes Lesch-Nyhan syndrome.
Step-by-step explanation:
Hypoxanthine phosphoribosyltransferase (HPRT) is an enzyme that plays a vital role in the purine salvage pathway. The correct function of HPRT in this pathway is to convert free bases like hypoxanthine and guanine into their respective nucleotides, to be more specific, it converts guanine to guanosine monophosphate (GMP) and hypoxanthine into inosine monophosphate (IMP), using 5-phosphoribosyl-1-pyrophosphate (PRPP) as a co-substrate. This salvage pathway is especially crucial in certain cell types like brain cells and leukocytes, which lack the mechanism for de novo purine synthesis. Lesch-Nyhan syndrome is a severe genetic disorder resulting from HPRT deficiency, leading to the accumulation of uric acid due to unrecycled guanine, xanthine, and hypoxanthine, and is characterized by neurological and behavioral abnormalities, predominantly in males.