PMID: 8271358Jul 1, 1993Paper

Use of the soluble peptide gamma-L-glutamyl-L-tyrosine to provide tyrosine in total parenteral nutrition in rats

JPEN. Journal of Parenteral and Enteral Nutrition
P G RadmacherD Adamkin


Limited solubility restricts amounts of tyrosine (Tyr) in amino acid solutions used in total parenteral nutrition (TPN). Excess phenylalanine (Phe) is included in TPN for conversion to Tyr by liver Phe hydroxylase. However, this conversion is limited, especially in infants. We have confirmed that infants receiving TPN have low Tyr concentrations and high Phe/Tyr ratios in plasma compared with published values for enterally fed neonates. Tyr is important in the synthesis of proteins and other biomolecules, including catecholamines in the brain. We tested the soluble peptide gamma-glutamyl-tyrosine (Glu(Tyr)) as a possible precursor of Tyr in TPN. Groups of five rats were given infusions of TPN containing an amino acid mixture simulating a commercial formulation (group A), TPN in which Glu(Tyr) was substituted for half the Phe in the group A solution) (group B), or saline (group C). Control animals (group C) were fed rodent chow. Blood was sampled at 0 time and daily for 4 days. Brains were collected at 96 hours, and aromatic amino acids in plasma and brains were measured by high-performance liquid chromatography. Throughout the experiment, plasma of animals in group A had significantly elevated Phe and reduced Tyr concentrations...Continue Reading


Oct 11, 1976·Biochimica Et Biophysica Acta·I KatzS Kaufman
Dec 1, 1979·Proceedings of the National Academy of Sciences of the United States of America·O W GriffithA Meister
Jun 27, 1978·Naunyn-Schmiedeberg's Archives of Pharmacology·A Carlsson, M Lindqvist
Jun 1, 1991·Metabolism: Clinical and Experimental·M HiltonD Adamkin
Jan 5, 1990·Science·M Barinaga
Apr 6, 1973·Science·A Meister
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Jan 1, 1983·Psychoneuroendocrinology·J M Lauder
May 24, 1983·Biochimica Et Biophysica Acta·M A ShotwellD L Oxender

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Jan 13, 1997·Biochemical and Biophysical Research Communications·T Marks, W R Farkas
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