2-Oxo-isocaproate

Bender DA (1989a) Effects of a dietary excess ofleucine and of the addition ofleucine and 2-oxo-isocaproate on the metabolism of tryptophan and niacin in isolated rat liver cells. British Journal of Nutrition 61, 629-40. 

Biosynthesis Leu is formed from pyruvic acid - 2-acetolactic acid [acetolactate synthase (EC 4.1.3.18.)+(l-hydroxyethyl)-TPP] - 2,3-dihydroxy-isovaleric acid [reductase+NAD(P)H] - 2-oxoisova-leric acid [dihydroxyacid dehydratase] - 2-isopropyl-malate [2-isopropylmalate synthase + acetyl-CoA (EC 4.1.3.12)] -> 3-isopropylmalate [isopropylmalate dehydratase (EC 4.2.1.33) -HjO+HiO] 2-oxo-isocaproate [3-isopropylmalate dehydrogenase (EC 1.1.1.85) + NAD ] L. [leucine aminotransferase (EC... 

Toxic metabolite Leucine and its keto add, 2-oxo-isocaproic acid Trial of 100-1,000 mg thiamine is completed by some metabolic centers for patients with variant forms of MSUD [1,2],... 

Of these, leucine and its corresponding keto acid, 2-oxo-isocaproic add, are the primary toxic compounds in this disorder (Box 16.1). Maple syrap urine disease is so named because patients with this disorder have a characteristic sweet odor detectable in the urine or cerumen. 

L-Leucine + 2-oxoglutarate - 2-oxo-isocaproate + L-glutamate This is a transaminase which reacts with 2-oxoglutarate of the citric acid cycle. 

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