These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Thyroxine (T4) release from thyroglobulin and its T4-containing peptide by thyroid thiol proteases.
    Author: Nakagawa H, Ohtaki S.
    Journal: Endocrinology; 1985 Apr; 116(4):1433-9. PubMed ID: 3918854.
    Abstract:
    Two thiol proteases, TP-1 and TP-2, were purified 500- and 400-fold, respectively, from hog thyroid lysosomal extracts and examined for their activities as releasers of T4 1) from hog thyroglobulin, 2) a fragment (mol wt, approximately 15,000) prepared therefrom, and 3) a T4-containing peptide (19 amino acid residues) derived from the fragment, by measuring the liberation of free T4 with reversed phase HPLC. TP-1 released 8%, 55%, and 95% of the bound T4 present in thyroglobulin, the fragment, and the peptide, respectively, after incubation for 8 h. TP-2, on the other hand, released only 2% of the bound T4 in thyroglobulin and liberated no T4 from the fragment and the peptide. The release of T4 from thyroglobulin by the action of TP-1 was increased approximately 2-fold by the addition of TP-2. This synergistic effect suggested that TP-1 can release T4 from thyroglobulin much more efficiently after the protein has been partially degraded by the action of TP-2, which has only a poor T4-releasing activity. It also suggested that the T4-releasing activity of TP-1 markedly increases as the size of protein substrate is decreased. The amino acid composition of the T4-containing peptide was identical with that previously isolated from bovine thyroglobulin, and this peptide sequence has been shown to be derived from the NH2-terminal portion of the thyroglobulin. This suggests that TP-1 can release T4 at least from the NH2-terminal region of thyroglobulin.
    [Abstract] [Full Text] [Related] [New Search]