Chronic Immune Stimulation May Cause Moderate Impairment of Phenylalanine 4-hydroxylase

Phenylalanine (4)-hydroxylase (PAH, E.C. 1.14.16.1) is located mainly in liver and converts amino acid phenylalanine (Phe) to tyrosine (Tyr). In 'classical' phenylketonuria (PKU), PAH activity is reduced, whereas in 'atypical' PKU biosynthesis of the cofactor 5,6,7,8-tetrahydrobi...

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Bibliographic Details
Published in:Pteridines 2011-02, Vol.22 (1), p.120-125
Main Authors: Scholl-Bürgi, S, Schroecksnadel, S, Jenny, M, Karall, D, Fuchs, D
Format: Article
Language:English
Subjects:
inflammation
neopterin
phenylalanine
phenylalanine hydroxylase
phenylalanine to tyrosine ratio
tyrosine
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Summary:Phenylalanine (4)-hydroxylase (PAH, E.C. 1.14.16.1) is located mainly in liver and converts amino acid phenylalanine (Phe) to tyrosine (Tyr). In 'classical' phenylketonuria (PKU), PAH activity is reduced, whereas in 'atypical' PKU biosynthesis of the cofactor 5,6,7,8-tetrahydrobiopterin (BH4) is disturbed. Aside from these inherited conditions, elevated plasma Phe concentrations and increased Phe to Tyr ratios (Phe/Tyr) were observed in patients with cancer, burns, sepsis and HIV-1 infection. Results indicate that immune activation and inflammation are associated with moderate impairment of PAH activity. This review discusses findings of increased Phe/Tyr in patients suffering from chronic inflammatory diseases, their clinical relevance and consequences.
ISSN:0933-4807
2195-4720
DOI:10.1515/pteridines.2011.22.1.120