The isolation and identification of N-isovalerylglycine from urine of patients with isovaleric acidemia.

A large amount of an unknown compound is found in urine of patients with isovaleric acidemia, an inborn error of leucine metabolism. Analytical data including nuclear magnetic resonance, mass and infrared spectra are presented, which establish the identity of this compound as N-isovalerylglycine. This report constitutes the first demonstration and isolation of N-isovalerylglycine from human material as well as from any other natural sources. Demonstration of this compound supports the assumption that the enzyme defect in these patients is at the level of conversion of isovaleryl coenzyme A to P-methylcrotonyl coenzyme A.