Isovalerylglycine (IVG) is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction: acyl-CoA + glycine < -- > CoA + N-acylglycine. Isovalerylglycine is a byproduct of the catabolism of the aminoacid leucine. Accumulation of isovalerylglycine occurs in Isovaleric Acidemia (IVA). IVA (OMIM/ McKusick 243500) is an autosomal recessive disorder caused by mutations in the isovaleryl-CoA dehydrogenase (EC 1.3.99.10) gene. The deficiency of this enzyme in the metabolism of leucine leads to the accumulation of a series of isovaleryl-CoA metabolites, such as isovalerylglycine. It is very important to caution for false positive results when screening for isovaleric acidemia by tandem mass spectrometry based on dried blood-spot levels of C5-acylcarnitines, including isovalerylcarnitine and its isomer, pivaloylcarnitine; pivaloylcarnitine is derived from pivalate-generating antibiotics, and has caused many false-positive results. Isovalerylglycine is a biomarker for the consumption of cheese.

Metabolism and Physiological Effects of Isovalerylglycine References