Secondary Products Derived from L-Leucine

L-Leucine is an a-amino acid with 6 C-atoms and a branched carbon chain. The secondary products formed from L-leucine in most cases still possess this iso-caproic acid structure. 

Secondary products are built from L-leucine in microorganisms and plants. Biosynthesis 

L-Leucine is derived from L-valine by the x-keto acid elongation system, i.e., via x-ketoisovaleric acid and -carboxy-j8-hydroxyisocaproic acid as outlined in Fig. 199. The transformation of ot-ketoisovaleric acid to (X-ketoisocaproic acid closely resembles the conversion of oxaloacetic acid to (X-ketoglutaric acid in the tricarboxylic acid cycle (D 5). x-Ketbacid elongation systems also participate in the formation of L-lysine via the x-aminoadipic acid pathway (D 18) and in the biosynthesis of a number of secondary amino acids which are precursors of gluco-sinolates (D 9.4). 

L-Leucine is degraded to acetoacetate and acetyl CoA on the pathway outlined in Fig. 200. 

1 Isopropylmalate synthase 2 isopropylmalate isomerase 3 carboxyhydroxyisocaproate decarboxylase 4 leucine aminotransferase 

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