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B6db references: 4831627

type Journal Article
authors David, J. C.; Dairman, W.; Udenfriend, S.
title On the importance of decarboxylation in the metabolism of phenylalanine, tyrosine, and tryptophan
journal Arch Biochem Biophys
sel selected
ui 4831627
year (1974)
volume 160
number 2
pages 561-8
keywords Administration, Oral
abstract After the oral administration of large doses of tyrosine, tryptophan, or phenylalanine to rats, increased plasma levels of these amino acids can be observed. These levels can be further elevated, approximately 2-fold, by administering along with the amino acids, inhibitors of aromatic-Image -amino acid decarboxylase. The inhibitors, by themselves, do not alter control plasma levels of the aromatic amino acids. This effect of the inhibitors appears to be specific for amino acids which are substrates of the decarboxylase since they did not further elevate plasma levels of leucine or valine after oral loading of these amino acids. Elevation of plasma tyrosine could also be observed after inhibition of the decarboxylase when tyrosine was administered intraperitoneally or in rats pretreated with antimicrobial agents, indicating that inhibition of decarboxylation by intestinal bacteria was not responsible for the effects. It was shown that the decarboxylase inhibitors do not act by simultaneously inhibiting other major routes of metabolism, such as transamination in the case of tyrosine. These findings indicate that, when tissue levels of tyrosine, phenylalanine, or tryptophan are elevated, decarboxylation becomes a major route for their metabolism.
last changed 2009/06/18 16:10

B6db references