The Mechanism of Cofactor Regeneration During Phenylalanine Hydroxylation

  • Steven W. Bailey
  • Scott R. Boerth
  • Shirley B. Dillard
  • June E. Ayling
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 338)


Although the ability of the liver to convert phenylalanine to tyrosine has been known since 19131, characterization of the components of the system did not begin until the mid 1950’s. Tetrahydrobiopterin was identified as the cofactor for the hydroxylase reaction2, which uses molecular oxygen as the source of the new hydroxyl group, Figure 1. It was first thought that only one other enzyme, dihydropteridine reductase (DHPR), was involved in the overall process. This converts the oxidized form of cofactor, a quinoid dihydropterin3, back to the starting tetrahydrobiopterin at the expense of NADH allowing cofactor to be used catalytically. The clinical symptoms of patients with a deficiency of DHPR have shown that cofactor regeneration is essential4.


Buffer Concentration Dehydration Reaction Phenylalanine Hydroxylase Cofactor Regeneration Plasma Phenylalanine 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    G. Embden and K. Baldes, Über den Abbau des Phenylalanins in Tierischen Organismus, Biochim. Z. 55:301–322 (1913).Google Scholar
  2. 2.
    S. Kaufman, The Structure of the Phenylalanine-Hydroxylation Cofactor. Proc. Natl. Acad. Sci. USA 50:1085–1093 (1963).PubMedCrossRefGoogle Scholar
  3. 3.
    S. Kaufman, Studies on the Structure of the Primary Oxidation Product Formed from Tetrahydropteridines during Phenylalanine Hydroxylation, J. Biol. Chem. 239:332–338 (1964).PubMedGoogle Scholar
  4. 4.
    R.G.H. Cotton, Inborn errors of pterin metabolism, in “Folates and Pterins”, Vol.3 R.L. Blakley and V.M. Whitehead, eds. Wiley & Sons, New York, (1986).Google Scholar
  5. 5.
    S. Kaufman and D.B. Fisher, Pterin-requiring aromatic amino acid hydroxylases, in Molecular Mechanisms of Oxygen Activation, O. Hayaishi, ed., Academic Press, New York, (1974).Google Scholar
  6. 6.
    S.W. Bailey, S.T. Weintraub, S.M. Hamilton, and J.E. Ayling, Incorporation of Molecular-Oxygen into Pyrimidine Cofactors by Phenylalanine-Hydroxylase, J. Biol. Chem. 257:8253–8260 (1982).PubMedGoogle Scholar
  7. 7.
    T.A. Dix, G.E. Bollag, P.L. Domanico, and S.J. Benkovic, Phenylalanine Hydroxylase: Absolute Configuration and Source of Oxygen of the 4a-Hydroxytetrahydropterin Species, Biochemistry 24:2955–2958 (1985).PubMedCrossRefGoogle Scholar
  8. 8.
    R.A. Lazarus, S.J. Benkovic, and S. Kaufman, Phenylalanine Hydroxylase Stimulator Protein is a 4a-Carbinolamine Dehydratase, J. Biol. Chem. 258:10960–10962 (1983).Google Scholar
  9. 9.
    R.A Lazarus, C.W. DeBrosse, and S.J. Benkovic, Phenylalanine Hydroxylase: Structural Determination of the Tetrahydropterin Intermediates by Carbon-13 NMR Spectroscopy, J. Am. Chem. Soc. ,104:6869–71 (1982).CrossRefGoogle Scholar
  10. 10.
    J. Haavik, K.A. Andersson, and T. Flatmark, Native and Phosphorylated Bovine Adrenal Tyrosine 3-Monooxygenase. Interactions with Tetrahydropterins and Substrate and Stability of the Formed 4a-Hydroxy-Tetrahydrobiopterin, Pteridines 1:11–16 (1989).CrossRefGoogle Scholar
  11. 11.
    M.D. Davis, and S. Kaufman, Evidence for the Formation of the 4a-Carbinolamine During the Tyrosine-dependent Oxidation of Tetrahydrobiopterin by Rat Liver Phenylalanine Hydroxylase, J. Biol. Chem. 264:8585–8596 (1989).PubMedGoogle Scholar
  12. 12.
    S.W. Bailey, R.Y. Chandrasekaran, and J.E. Ayling, Synthesis of Tetrahydropteridine C6-Stereoisomers, Including N5-Formyl-(6S)-tetrahydrofolic Acid, J. Org. Chem. 57:4470–4477 (1992).CrossRefGoogle Scholar
  13. 13.
    S.W. Bailey and J.E. Ayling, 6,6-Dimethylpterins: Stable Quinoid Dihydropterin Substrate for Dihydropteridine Reductase and Tetrahydropterin Cofactor for Phenylalanine Hydroxylase, Biochemistry 22:1790–1799 (1983).PubMedCrossRefGoogle Scholar
  14. 14.
    S.W. Bailey, S.R. Boerth, and J.E. Ayling, manuscript in preparation (1993).Google Scholar
  15. 15.
    A. Albert, Covalent hydration of pteridines, in “Pteridine Chemistry”, W. Pfleiderer and E.C. Taylor, eds. Macmillan Co., New York (1964).Google Scholar
  16. 16.
    S. Kaufman, Phenylketonuria: biochemical mechanisms, in “Advances in Neurochemistry”, B.W. Agranoff and M.H. Aprison, eds., Plenum Press, New York, (1977).Google Scholar
  17. 17.
    S. Milstien and S. Kaufman, Studies on the Phenylalanine Hydroxylase System in Vivo, J. Biol. Chem. 250:4782–4785 (1975).PubMedGoogle Scholar
  18. 18.
    K.N. Antonas, W.F. Coulson, and J.B. Jepson, Simulation of Phenylketonuria in Rats by Extended p-Chlorophenylalanine Treatment, Biochem. Soc. Trans. 2:105–107 (1974).Google Scholar
  19. 19.
    M.A. Lipton, R. Gordon, G. Guroff, and S. Udenfriend, p-Chlorophenylalanine-Induced Chemical Manifestations of Phenylketonuria in Rats, Science 156:248–250 (1967).PubMedCrossRefGoogle Scholar
  20. 20.
    M.B. Youdim, B. Mitchell, H.F. Woods, The Effect of Increasing Phenylalanine Concentration on Phenylalanine Metabolism in Perfused Rat Liver, Biochem. Soc. Trans. 3:683–684 (1975).PubMedGoogle Scholar
  21. 21.
    B.A. Citron, M.D. Davis, S. Milstien, J. Gutierrez, D.B. Mendel, G.R. Crabtree, and S. Kaufman, Identity of 4a-Carbinolamine Dehydratase, a Component of the Phenylalanine Hydroxylase System, and DCoH, a Transregulator of Homeodomain Proteins, Proc. Natl. Acad. Sci. USA 89:11891–11894 (1992).PubMedCrossRefGoogle Scholar
  22. 22.
    C.R. Hauer, I. Rebrin, B. Thöny, F. Neuheiser, H.C. Curtius, P. Hunziker, N. Blau, S. Gisla, and C.W. Heizmann, Phenylalanine Hydroxylase-stimulating Protein/Pterin-4a-carbinolamine Dehydratase from Rat and Human Liver, J. Biol Chem. 268:4828–4831 (1993).PubMedGoogle Scholar
  23. 23.
    M.D. Davis, S. Kaufman, and S. Milstien, Distribution of 4a-Hydroxytetrahydropterin Dehydratase in Rat Tissues-Comparison with the Aromatic Amino Acid Hydroxylases, FEBS Letters 302:73–76 (1992).PubMedCrossRefGoogle Scholar
  24. 24.
    H.C. Curtius, C. Adler, I. Rebrin, C. Heizmann, and S. Ghisla, 7-Substituted Pterins: Formation During Phenylalanine Hydroxylation in the Absence of Dehydratase, Biochem. Biophys. Res. Commun. 172:1060–1066 (1990).PubMedCrossRefGoogle Scholar
  25. 25.
    M.D. Davis, S. Kaufman, and S. Milstien, Conversion of 6-Substituted Tetrahydropterins to 7-Isomers via Phenylalanine Hydroxylase Generated Intermediates, Proc. Natl. Acad. Sci. USA 88:385–389 (1991).PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1993

Authors and Affiliations

  • Steven W. Bailey
    • 1
  • Scott R. Boerth
    • 1
  • Shirley B. Dillard
    • 1
  • June E. Ayling
    • 1
  1. 1.Department of Pharmacology College of MedicineUniversity of South AlabamaMobileUSA

Personalised recommendations