Dietary methionine and the excretion of formiminoglutamic acid by the rat.

Formiminoglutamic acid is a product derived from the metabolism of histidine by mammalian liver and several microorganisms (l-3). The metabolism of FGA’ is dependent upon the presence of tetrahydrofolic acid (4, 5), and consequently this formimino compound is excreted in the urine of human subjects or laboratory rats which have a deficiency of folic acid (6-8). Daft (6) has reported that suitable amino acid mixtures will partially replace the need for folic acid in the growth of the laboratory rat. Therefore, a study was undertaken to determine the influence of amino acids on the excretion of FGA in the urine of the rat. It was found that dietary methionine significantly reduces the excretion of FGA. We shall describe these observations and the implications derived therefrom.