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Thyroid Hormones and D ‐Aspartic Acid, D ‐Aspartate Oxidase, D ‐Aspartate Racemase, H 2 O 2 , and ROS in Rats and Mice
Author(s) -
Topo Enza,
Fisher George,
Sorricelli Andrea,
Errico Francesco,
Usiello Alessandro,
D'Aniello Antimo
Publication year - 2010
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200900360
Subject(s) - chemistry , thyroid , medicine , endocrinology , biochemistry , hormone , biology
Abstract Total concentrations of thyroid hormones T 3 and T 4 , and of their free forms, FT 3 and FT 4 , D ‐aspartic acid ( D ‐Asp), D ‐aspartate oxidase ( D ‐AspO), D ‐aspartate racemase, H 2 O 2 , and ROS (reactive oxygen species) were determined in rats and mice. T 3 and T 4 were 1 and 50 ng/ml, respectively, in serum, and 750 and 40000 ng/g, respectively, in thyroid. Concentrations of the free forms FT 3 and FT 4 were ca. 250 times lower than their respective total concentrations. The endogenous content of D ‐Asp in thyroid gland was ca. 100 nmol/g tissue, whereas the activity of D ‐AspO was ca. 80 units/mg thyroid, and that of D ‐aspartate racemase was ca. 15 units/mg thyroid. H 2 O 2 Concentration in rat and mouse thyroid gland was ca. 290 pmol/g thyroid, and the concentration of ROS was ca. 10 pmol/DCF/min/mg protein. H 2 O 2 is essential for the iodination of the tyrosyl residues to produce mono‐ and diiodotyrosine that are the precursors for the synthesis of T 3 and T 4 . Production of H 2 O 2 in thyroid glands occurs by oxidation of endogenous D ‐Asp by D ‐AspO ( D ‐Asp+O 2 +H 2 O→ α ‐oxaloacetate+NH 3 +H 2 O 2 ). D ‐Aspartate racemase catalyzes the in vivo production of D ‐Asp from L ‐Asp. Thus, interaction of endogenous D ‐Asp, D ‐AspO, and D ‐aspartate racemase in thyroid gland constitutes an additional biochemical pathway for the production of H 2 O 2 and consequently for the synthesis of thyroid hormones.