A Short Assay for the Estimation of Dietary Purine Compounds, Using a Rat Model System with Inhibition of Uricase

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Abstract
A model system for purine metabolism employing young rats fed potassium oxonate (an inhibitor of uricase) was used for screening the total purine contents in microbial cell materials. Graded amounts of isolated yeast-RNA were added to a low purine diet containing 3% oxonate and the increases in plasma uric acid level (PUA) were measured after one day's feeding. AT low dietary concentrations of RNA, the PUA level was found to be an almost linear function of the amount of RNA consumed. The curves thus obtained were used as standard curves in order to assay materials with unknown nucleic acid contents. Three microbial samples were tested, namely bacteria, yeast, and a yeast protein concentrate with a reduced content of nucleic acids. Two assays, performed under somewhat different conditions, gave the following values for nucleic acid contents expressed as percentage RNA on a dry weight basis: bacteria 13.2 and 14.4, yeast 4.8 and 4.5, yeast protein concentrate 3.0 and 2.7, respectively.