Ribonuclease and deoxyribonuclease, which are produced in the pancreatic juice, convert RNA and DNA primarily to oligonucleotides. This is further degraded to 3′- and 5′-mononucleotides by the enzyme pancreatic phosphodiesterase. A group of nucleotides degrade phosphate and release the bases before uptake (dietary purines and pyrimidines are not utilised for the synthesis of uric acid). The purine bases are further catabolised to uric acid by the intestinal mucosal cells and are finally excreted in the urine. The remnants of purine bases are metabolised by intestinal flora. The summary of this pathway is shown in Figure 11.1.

Figure 11.1 Digestion of Dietary Nucleic Acids