Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Myeloperoxidase-catalyzed iodination and coupling.

A Taurog1, M L Dorris

  • 1Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235.

Archives of Biochemistry and Biophysics
|July 1, 1992
PubMed
Summary

Myeloperoxidase (MPO) can iodinate and couple thyroglobulin to form thyroxine, similar to thyroid peroxidase (TPO). MPO activity is influenced by pH and halide ions, and inhibited by thioureylene drugs.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

The relation of the thyroxine content of the thyroid gland and of the level of protein-bound iodine of plasma to iodine intake.

The Journal of biological chemistry·2010
Same author

The structural specificity of sulfanilamide-like compounds as inhibitors of the invitro conversion of inorganic iodide to thyroxine and diiodotyrosine by thyroid tissue.

The Journal of biological chemistry·2010
Same author

The influence of hypophysectomy upon plasma iodine and thyroxine content of the thyroid gland of the rat.

Endocrinology·2010
Same author

On the determination of plasma iodine.

The Journal of biological chemistry·2010
Same author

The determination of thyroxine in the thyroid gland of the rat.

The Journal of biological chemistry·2010
Same author

The metabolic interrelations of thyroxine and diiodotyrosine in the thyroid gland as shown by a study of their specific activity-time relations in rats injected with radioactive iodine.

The Journal of biological chemistry·2010

Area of Science:

  • Biochemistry
  • Enzymology
  • Thyroid Hormone Synthesis

Background:

  • Myeloperoxidase (MPO) shares sequence homology with thyroid peroxidase (TPO) and lactoperoxidase (LPO).
  • The enzymatic activities of MPO in relation to thyroid hormone synthesis are not fully understood.

Purpose of the Study:

  • To investigate the catalytic activities of MPO in iodinating and coupling thyroglobulin.
  • To compare MPO's enzymatic properties with those of TPO and LPO.

Main Methods:

  • Enzymatic assays were performed using goiter thyroglobulin, iodide, and hydrogen peroxide.
  • pH optima for iodination were determined under various conditions, including the presence of chloride or bromide ions.
  • Coupling activity was assessed in the absence of iodination.
  • Inhibition studies were conducted using thioureylene drugs.

Main Results:

  • MPO exhibited an acidic pH optimum (around 4.0) for iodination, distinct from TPO and LPO.
  • Chloride or bromide ions shifted MPO's pH optimum to 5.4 and stimulated its iodinating activity at this pH.
  • MPO demonstrated significant coupling activity, comparable to TPO, and was stimulated by diiodotyrosine.
  • MPO-catalyzed iodination was inhibited by propylthiouracil and methimazole, similar to TPO.

Conclusions:

  • Myeloperoxidase possesses both iodinating and coupling activities relevant to thyroxine formation.
  • MPO's enzymatic characteristics, including pH optima and response to halides, differ from TPO and LPO.
  • MPO represents a potential alternative enzyme in thyroid hormone synthesis pathways.

Related Experiment Videos