N-Isovalerylalanine and N-isovalerylsarcosine: two new minor metabolites in isovaleric acidemia.

Besides N-isovalerylglycine, isovaleric, 3-hydroxyisovaleric, 4-hydroxyisovaleric, methylsuccinic, mesaconic, 3-hydroxyisoheptanoic and N-isovalerylglutamic acids the excretion of hitherto unreported N-isovalerylalanine and N-isovalerylsarcosine, two minor but characteristic constituents of the organic acid profile in isovaleric acidemia, is described. The new metabolites are assumed to be formed from isovaleryl-CoA by action of the enzyme glycine N-acylase on alanine and sarcosine, respectively.