Amino acid degradation threonine dehydratase

L-Threonine is an absolute dietary essential amino acid. The degradation of the threonine can be via a dehydratase or a specific aldolase in the liver. 

L-lsoieucine, lie L-a-amino-P-methylvaleric acid, CH3-CH2-CH(CH3)-CH(NH2)-C00H, an aliphatic, neutral amino acid found in proteins. He is found in relatively large amounts in hemoglobin, edestin, casein and serum proteins, and in sugar beet molasses, from which it was first isolated in 1904 by F. Ehrlich. It is an essential dietary amino acid, and is both glu-coplastic (degradation via propionic acid) and keto-plastic (formation of acetate) (see Leucine), The biosynthesis of He starts with oxobutyrate and pyruvate. Oxobutyrate is synthesized by deamination of L-threonine by threonine dehydratase (threonine de-... 

The initial reaction associated with isoleucine biosynthesis is catalyzed by threonine dehydratase (18). In microorganisms and a few plants, both degra-dative and biosynthetic enzymes have been identified. The former are not regulated by amino acids, but some are activated by AMP or ADP. An apparently unregulated threonine dehydratase has been purified from seeds of Cus-cuta campestris (Madan and Nath, 1983). The lack of identifiable regulatory phenomena precludes identification of the function of this enzyme as either biosynthetic or degradative in nature. 

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