QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sidransky, H. Articles by Schwartz, A. M. Search for Related Content PubMed PubMed Citation Articles by Sidransky, H. Articles by Schwartz, A. M.

Indolic Compounds Affect Tryptophan Binding to Rat Hepatic Nuclei^{1, 2,}

Department of Pathology, The George Washington University Medical Center, Washington, DC 20037

This study evaluates the effects of indolic or indole-related compounds on binding of L-tryptophan (saturable, stereospecific and of high affinity) to rat hepatic nuclei or nuclear envelopes. Addition of any one of many indolic or indole-related compounds, and particularly of 3-methylindole, does not inhibit in vitro binding of [³H]tryptophan to hepatic nuclear envelopes. However, when 3-methylindole (10^-10 to 10^-4 mol/L) is added in combination with unlabeled L-tryptophan (10^-4 mol/L), it diminishes the inhibitory effect of unlabeled L-tryptophan alone. Scatchard analysis of the binding affinities of in vitro [³H]tryptophan binding to hepatic nuclear envelopes using L-tryptophan in the absence or presence of 3-methylindole reveals similar dissociation constants (K_D) under the two conditions, but the binding concentrations (B_max) were greater in the combined group compared with that in the L-tryptophan alone group. Addition of 3-methylindole to liver before homogenization decreases specific [³H]tryptophan binding to nuclei compared with controls (without addition). L-Tryptophan tube-fed to rats with or without 3-methylindole administration increases in vitro hepatic protein synthesis compared with that of saline tube-fed controls. 3-Methylindole itself does not affect protein synthesis. Our report describes the effects of 3-methylindole on specific tryptophan binding to hepatic nuclear envelope receptor and discusses the possible implications thereof.

KEY WORDS: • L-tryptophan • indolic compounds • hepatic • nuclear envelope binding • rats

¹ Supported by a research grant from Showa Denko KK and by U.S. Public Health Service research grant DK 45353 from the National Institute of Arthritis, Diabetes, and Digestive and Kidney Disease.

² The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 USC section 1734 solely to indicate this fact.

³ To whom correspondence should be addressed.

Manuscript received 17 August 1993. Revision accepted 11 January 1994.