Halenaquinol, a natural cardioactive pentacyclic hydroquinone, interacts with sulfhydryls on rat brain Na+, K+-ATPase

Irina A. Gorshkova, Boris A. Gorshkov, Sergey A. Fedoreev, Valentin A. Stonik

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Halenaquinol inhibited the partial reactions of ATP hydrolysis by rat brain cortex Na+, K+-ATPase, such as [3H]ATP binding to the enzyme, Na+-dependent front-door phosphorylation from [γ-33P]ATP, and also Na+- and K+-dependent E1↔E2 conformational transitions of the enzyme. Halenaquinol abolished the positive cooperativity between the Na+- and K+-binding sites on the enzyme. ATP and sulfhydryl-containing reagents (cysteine and dithiothreitol) protected the Na+, K+-ATPase against inhibition. Halenaquinol can react with additional vital groups in the enzyme after blockage of certain sulfhydryl groups with 5,5′-dithio-bis-nitrobenzoic acid. Halenaquinol inhibited [3H]ouabain binding to Na+, K+-ATPase under phosphorylating and non-phosphorylating conditions. Binding of fluorescein 5′-isothiocyanate to Na+, K+-ATPase and intensity of fluorescence of enzyme tryptophanyl residues were decreased by halenaquinol. We suggest that interaction of halenaquinol with the essential sulfhydryls in/or near the ATP-binding site of Na+, K+-ATPase resulted in a change of protein conformation and subsequent alteration of overall and partial enzymatic reactions.

Original languageEnglish (US)
Pages (from-to)531-540
Number of pages10
JournalComparative Biochemistry and Physiology - C Toxicology and Pharmacology
Volume128
Issue number4
DOIs
StatePublished - Jan 1 2001

Keywords

  • Halenaquinol
  • Inhibition
  • Marine natural products
  • Na+, K-ATPase
  • Petrosia seriata
  • Rat brain
  • Sponge
  • Sulfhydryls

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Toxicology
  • Cell Biology
  • Health, Toxicology and Mutagenesis

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