The Nutritive Value and Safety of D-Phenylalanine and D-Tyrosine in Mice
1984; Elsevier BV; Volume: 114; Issue: 11 Linguagem: Inglês
10.1093/jn/114.11.2089
ISSN1541-6100
AutoresMendel Friedman, Michael R. Gumbmann,
Tópico(s)Polyamine Metabolism and Applications
ResumoGrowth studies in mice fed synthetic amino acid diets showed that: 1) the biological utilization of D-phenylalanine relative to its L-isomer ranged from 28-81%, depending on the respective concentrations of these amino acids in the diet; 2) L-tyrosine can replace about one-half of the L-phenylalanine needed to achieve maximum weight gain and 3) D-tyrosine has no similar sparing effect on L-phenylalanine. In fact, addition of D-tyrosine to amino acid or casein diets depressed weight gain to 10% that of the control. This inhibition was significantly reduced by increasing the L-phenylalanine content of the amino acid diets and the protein content of the casein diets. Growth inhibition, therefore, appears to be related to the ratio of D-tyrosine to L-phenylalanine and possibly other amino acids in the diet, rather than to the absolute levels of D-tyrosine. Mechanistic rationalizations are offered to account for the toxic or antinutritional manifestation of D-tyrosine.
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