The metabolism of L-m-tyrosine: the use of a putative precursor to investigate the increased production of m-hydroxymandelic acid in phenylketonuria.

Abstract

Several urinary meta-substituted phenols appear to be of endogenous origin. However, the production of these compounds is reduced in phenylketonuria with the exception of m-hydroxymandelic acid whose excretion is approximately doubled. This phenomenon has been investigated in two patients with phenylketonuria using the putative precursor L-m-tyrosine labelled with deuterium. Metabolism of this compound in these patients was comparable to that in healthy adults although much less was converted to m-hydroxymandelic acid and the excretion pattern of this metabolite was different. This apparent anomaly is attributed to smaller metabolic compartments in phenylketonuria and a lower threshold for the metabolism of m-tyramine via beta-hydroxylation. Incorporation into the natural pathway was shown by depletion of endogenous m-hydroxymandelic acid. The results are further support for the ideas that the amine precursors of m-hydroxymandelic acid, m-tyramine and m-octopamine, have a functional role and may be important in the pathogenesis of phenylketonuria.

• Authors: J A Hoskins, A M Greenway
• Journal: Clinica chimica acta; international journal of clinical chemistry (Clin Chim Acta) Vol. 130 Issue 3 Pg. 329-38 (Jun 15 1983) ISSN: 0009-8981 [Print] Netherlands
• PMID: 6872265 (Publication Type: Journal Article)

Chemical References

• Mandelic Acids
• Phenylacetates
• 3,4-Dihydroxyphenylacetic Acid
• Octopamine
• 3-hydroxymandelic acid
• Tyrosine
• 2-Hydroxyphenethylamine
• norfenefrine
• 3-tyrosine
• 3-hydroxybenzeneacetic acid

Topics

• 2-Hydroxyphenethylamine (analogs & derivatives, metabolism)
• 3,4-Dihydroxyphenylacetic Acid (urine)
• Adult
• Female
• Humans
• Hydroxylation
• Kinetics
• Male
• Mandelic Acids (urine)
• Octopamine (analogs & derivatives)
• Phenylacetates (urine)
• Phenylketonurias (metabolism)
• Tyrosine (metabolism)