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 language | English (US) |
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Pages (from-to) | 531-540 |
Number of pages | 10 |
Journal | Comparative Biochemistry and Physiology - C Toxicology and Pharmacology |
Volume | 128 |
Issue number | 4 |
DOIs | |
State | Published - 2001 |
Externally published | Yes |
Keywords
- Halenaquinol
- Inhibition
- Marine natural products
- Na+, K-ATPase
- Petrosia seriata
- Rat brain
- Sponge
- Sulfhydryls
ASJC Scopus subject areas
- Biochemistry
- Physiology
- Aquatic Science
- Animal Science and Zoology
- Toxicology
- Cell Biology
- Health, Toxicology and Mutagenesis