Xanthine is a product
of purine catabolism. It is produced as a result of deamination
of guanine (Figure 22.7) by guanine
deaminase or by the reaction catalyzed by xanthine oxidase. These
reactions are as follows:
Xanthine is a product
of purine catabolism. It is produced as a result of deamination
of guanine (Figure 22.7) by guanine
deaminase or by the reaction catalyzed by xanthine oxidase. These
reactions are as follows:
Guanine + H2O <=> Xanthine + NH3 (Guanine Deaminase)
Hypoxanthine + O2 <=> Xanthine + H2O2 (Xanthine Oxidase)
Xanthine oxidase can oxidize xanthine further to uric acid, as well (Figure 22.7)
Allopurinol, which is similar to hypoxanthine (see here), is used to treat gout because it inhibits xanthine oxidase, leading to accumulation of hypoxanthine and xanthine, both of which are more soluble and more readily excreted than uric acid (the causative agent of gout).