Metabolism of the following amino acid give rise to an intermediate product, FIGLU:
Catabolism of histidine proceeds urocanate, 4-imidazolone-5-propionate, and N-formiminoglutamate (Figlu). Formimino group transfer to tetrahydrofolate forms glutamate, then alpha-ketoglutarate. In folic acid deficiency, transfer of the formimino group is impaired, and Figlu is excreted. Excretion of Figlu following a dose of histidine thus can be used to detect folic acid deficiency. Benign disorders of histidine catabolism include histidinemia and urocanic aciduria associated with impaired histidase. Ref: Rodwell V.W. (2011). Chapter 29. Catabolism of the Carbon Skeletons of Amino Acids. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.
Histidine
Arginine
Cystine
Methionine