Interactions of indoles with specific binding sites for 2,3,7,8-tetrachlorobenzo-p-dioxin in rat liver

M. Gillner, J. Bergman, C. Cambillau, B. Fernström, Jan-Ake Gustafsson

Research output: Contribution to journalArticle

147 Scopus citations

Abstract

In order to identify some of the structural requirements for binding of indoles to the receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), we have investigated the capacity of various indoles to inhibit specific [1,6-3H]TCDD binding in rat liver cytosol, as analyzed by electrofocusing in polyacrylamide gel. Of these indoles, indolo[3,2-b]carbazole was the most active. The IC50 value for receptor binding of indolo[3,2-b]carbazole as well as for 2,3,7,8-tetrachlorodibenzofuran was 3.6 nM, whereas that of 5,6-benzoflavone was 26 nM. Both indolo[3,2-b]carbazole and 2,3,7,8-tetrachlorodibenzofuran competitively inhibited the binding of [3H]TCDD to the receptor. The well-known microsomal enzyme inducer 3,3'-diindolylmethane did not interact significantly with the TCDD receptor. Previous concepts of structure-activity relationships for binding of chlorinated dioxins to the TCDD receptor fail to account for the receptor binding of unhalogenated aryl hydrocarbon hydroxylase inducers such as 5,6-benzoflavone. We have instead considered the true three-dimensional space occupied by some receptor ligands by means of a computer using crystallographic data as inputs. When the atomic van der Waals radii were included, all potent receptor ligands studied could be fitted into a rectangle of 6.8 x 13.7 Å.

Original languageEnglish (US)
Pages (from-to)357-363
Number of pages7
JournalMolecular Pharmacology
Volume28
Issue number4
StatePublished - Dec 1 1985

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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