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: Enantioselective sulfation of beta 2-receptor agonists by the human intestine and the recombinant M-form phenolsulfotransferase.
    Author: Hartman AP, Wilson AA, Wilson HM, Aberg G, Falany CN, Walle T.
    Journal: Chirality; 1998; 10(9):800-3. PubMed ID: 9839429.
    Abstract:
    The beta 2-receptor agonist class of drugs is metabolized in humans almost exclusively by sulfate conjugation. The objective of this investigation was to determine the influence of chemical structure on the stereoselectivity of the sulfoconjugation of these chiral drugs. The pure enantiomers of six beta 2-agonists, including those clinically most widely used, were all effectively sulfated both by the cytosol of the human intestine and the recombinant human M-form phenolsulfotransferase (PST). Whereas the apparent Km values (Km,app) for the sulfation of the individual drug enantiomers by the intestinal cytosol varied widely, ranging from 4.8 microM for (S)-isoproterenol to 889 microM for (S)-albuterol, these Km,app values were highly correlated with those obtained with M-PST (correlation coefficient 0.994). In contrast, the M-PST Vmax,app values were similar for all drug enantiomers, ranging from 276 to 914 pmol min-1 mg-1 protein, implying that substrate binding to M-PST by far is the main determinant of the sulfation activity. For isoproterenol, the Km,app for M-PST was 6.1 times higher for the active (R)- than for the inactive (S)-enantiomer. For other beta 2-agonists, the stereoselectivity decreased towards unity as the Km,app increased. However, for albuterol, containing a hydroxymethyl substituent at the aromatic ring, the stereoselectivity was dramatically reversed, with 10 times higher Km,app for the inactive (S)- than for the active (R)-enantiomer.
    [Abstract] [Full Text] [Related] [New Search]