Effect of dietary threonine supplementation on tyrosine toxicity in the rat

Datta, Kasturi ; Ghosh, J. J. (1977) Effect of dietary threonine supplementation on tyrosine toxicity in the rat The Journal of Nutrition, 109 (9). p. 1575. ISSN 0022-3166

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Official URL: http://jn.nutrition.org/cgi/content/abstract/107/9...


The objective of this study was to determine the effect of threonine supplementation on tyrosine metabolism in rats fed a low protein diet with excess tyrosine. The growth retardation and the development of eye and paw lesions that occur in rats ingesting a basal plus 3% or 5% L-tyrosine diet could be alleviated partially by the addition of 0.5% or 1.0% L-threonine to the diet. An increased blood tyrosine level in rats fed excess tyrosine was also lowered by threonine supplementation. In tyrotoxic conditions, the activities of liver tyrosine transaminase (EC and threonine dehydratase (EC were elevated, but p-hydroxyphenyl pyruvic acid oxidase (EC which is also intimately associated with tyrosine toxicity was found to be inactivated. Furthermore, biosyn thesis of ascorbic acid in liver was significantly lowered in this condition. However, addition of L-threonine in the diet, not only could cure the signs developed due to excess tyrosine, but also could affect the levels of enzymes studied.

Item Type:Article
Source:Copyright of this article belongs to American Society for Nutritional Sciences.
Keywords:Tyrosine Toxicity; Threonine Alleviation; Tyrosine Transaminase; pHPP Oxidase; Threonine Dehydratase; Ascorbic Acid Biosynthesis
ID Code:9095
Deposited On:29 Oct 2010 11:40
Last Modified:16 May 2016 18:57

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