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: Steroid 3- and 17-OH UDP-glucuronosyltransferase activities in rat and rabbit liver microsomes.
    Author: Falany CN, Chowdhury JR, Chowdhury NR, Tephly TR.
    Journal: Drug Metab Dispos; 1983; 11(5):426-32. PubMed ID: 6138227.
    Abstract:
    Steroid glucuronidation was investigated in solubilized female rat and rabbit liver microsomes and in preparations of UDP-glucuronsyltransferase (UDPGT) activity resolved from these organelles. Solubilized rabbit liver microsomes possessed relatively high UDPGT activity towards estrone and beta-estradiol but not testosterone. Glucuronidation observed at the 3-OH position of beta-estradiol is 20-fold greater than at the 17-OH position. Estrone UDPGT activity, highly purified from rabbit liver microsomes, was active towards estrone and the 3-OH position of beta-estradiol but not towards testosterone (17-OH) or the 17-OH position of beta-estradiol. Thus, estrone UDPGT activity demonstrated essentially the same specificity for conjugation of the 3-OH position of beta-estradiol as observed in microsomes. Solubilized liver microsomes from female rats possessed approximately 4-fold more activity towards testosterone (17-OH) than estrone (3-OH). Rat liver microsomes formed about 2.5-fold more beta-estradiol 17-glucuronide than 3-glucuronide. Following a Chromatofocusing procedure where a gradient from pH 9-7 was employed, an eluant fraction was obtained that was enriched in estrone UDPGT activity relative to testosterone UDPGT activity. The fraction preferentially conjugated the 3-OH position of beta-estradiol. Two eluant fractions were obtained which demonstrated high levels of UDPGT activity towards testosterone and beta-estradiol but not estrone. Both fractions possessed a UDPGT activity that displayed a high degree of specificity for conjugation of the 17-OH position of beta-estradiol. A 17-OH steroid UDPGT was purified to apparent homogeneity from one of these fractions. These results suggest that separate UDPGT activity exists in female rat liver for the glucuronidation of the 3- and 17-OH positions of beta-estradiol. In female rabbit liver, beta-estradiol is predominantly conjugated at the 3-OH position by a single form of UDPGT.
    [Abstract] [Full Text] [Related] [New Search]