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Kinetic Properties of Human Liver Tryptophan Pyrrolase

  • Y. Minatogawa
  • I. S. L. Matsui
  • R. Kido
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 294)

Abstract

Human liver tryptophan pyrrolase (TPO) activity exhibited substrate level regulation. TPO showed biphasic activity to tryptophan when low ascorbate was used as an activator. The high affinity form (Km for tryptophan: 0.05 mM) was promoted by low ascorbate and low tryptophan. The low affinity form(Km for tryptophan: 0.4 mM) was induced by high concentrations of tryptophan or ascorbate. Both high and low affinity forms showed the same affinity to oxygen. The high affinity form was also induced by pyrroloquinoline quinone, but this effect was decreased by catalase, suggesting the participation of H202.

Keywords

Affinity Form Pyrroloquinoline Quinone Biphasic Activity Tryptophan Pyrrolase High Ascorbate 
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.

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References

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Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • Y. Minatogawa
    • 1
  • I. S. L. Matsui
    • 1
  • R. Kido
    • 1
  1. 1.Department of BiochemistryWakayama Medical CollegeWakayama 640Japan

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