FURTHER STUDIES ON THE METABOLISM OF UROCANIC-α-C14 ACID

The existence of radioactive metabolites in the liver extracts of rats a short time after injection of urocanic-α-C14 acid has been investigated. Glutamic acid, N-formiminoglutamic acid, and an unknown compound that yields glutamic acid on hydrolysis were the major urocanic acid catabolites found therein. These three substances accounted for as much as 75% of the total radiocarbon in the extracts. The sole catabolic pathway of importance for urocanic acid, in the rat, is the formation of glutamic acid. Since formylglutamic acid could not be detected in these extracts, the role of this substance as an obligatory urocanic acid catabolite becomes questionable.