STUDIES OF PURINE METABOLISM

Purine chemistry dates back to 1776 when Scheele discovered uric acid in human urine. This was followed a century later by the discovery of guanine (Fig. 1) by Unger (1846), of nucleic acids by Meischer (1871) and of adenine by Kossel (1885). The recognition of an association of purines and nucleic acids with the nuclei of cells led to many studies of the distribution and the functions of the purines. Rose has pointed out, in his comprehensive review (1923) of the early studies on purines, that attempts to study the distributions and functions of the purines are among the earliest metabolic studies on record. The fact that the animal organism does not require the presence in the diet of preformed purines or pyrimidines for the formation of nucleic acids made difficult the application of