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Home / Equine Research Bank / Protein J / Inhibitor Action of Unsaturated Fatty Acids on Equine Serum ...
The protein journal2025; 44(3); 271-282; doi: 10.1007/s10930-025-10259-8

Inhibitor Action of Unsaturated Fatty Acids on Equine Serum Butyrylcholinesterase.

Abstract: Butyrylcholinesterase (BChE; EC 3.1.1.8), a serine hydrolase found in various tissues, hydrolyses choline esters such as acetylcholine and succinylcholine, as well as other esters such as heroin and acetylsalicylic acid. It is considered to play a role in lipid metabolism as it belongs to the same enzyme group as lipases and its catalytic subunits are similar. In this study, the effects of unsaturated fatty acids, namely arachidonic (AA), linoleic (LA), alpha-linolenic (ALA) and oleic acid (OA), on equine serum BChE (EqBChE) were investigated. Enzyme activity was measured by the modified Ellman method. When the activity results were evaluated, the IC50 values were found 45.49, 8.465, 1556, and 56.57 μM; while the Ki values were 63.92, 11.46, 1800, and 15.24 μM for AA, ALA, LA, and OA, respectively. Analysis of the kinetic results showed that ALA was compatible with mixed inhibition and other fatty acids were compatible with non-competitive inhibition, a special type of mixed inhibition. Molecular docking predicted binding of the fatty acids to the active site, as well as to predicted allosteric sites. The results of this study provide another support to the hypothesis that cholinesterases are associated with lipid metabolism.
© 2025. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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Publication Date: 2025-02-22 PubMed ID: 39987389PubMed Central: 50435DOI: 10.1007/s10930-025-10259-8Google Scholar: Lookup
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Summary

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Equine serum butyrylcholinesterase (EqBChE) activity is inhibited by certain unsaturated fatty acids, suggesting a regulatory link between cholinesterase function and lipid metabolism. This study measured how specific fatty acids affect EqBChE enzyme activity and explored their inhibition mechanisms.

Background and Purpose

  • Butyrylcholinesterase (BChE) is a serine hydrolase enzyme present in various tissues that hydrolyzes choline esters like acetylcholine and other esters such as heroin and acetylsalicylic acid.
  • BChE is related to lipases and may play a role in lipid metabolism due to similarities in catalytic subunits.
  • The study aimed to investigate how unsaturated fatty acids impact the activity of equine serum BChE (EqBChE) and to understand the mechanism of inhibition.

Methodology

  • Four specific unsaturated fatty acids were selected: arachidonic acid (AA), linoleic acid (LA), alpha-linolenic acid (ALA), and oleic acid (OA).
  • Enzyme activity of EqBChE was measured using the modified Ellman method, a colorimetric assay commonly used to assess cholinesterase activity.
  • Inhibition parameters such as IC50 (concentration for 50% inhibition) and Ki (inhibition constant) values were calculated for each fatty acid.
  • Kinetic analyses were performed to classify the type of inhibition exhibited by each fatty acid.
  • Molecular docking simulations were conducted to predict the binding sites of these fatty acids on EqBChE, including both the active and potential allosteric sites.

Key Findings

  • The IC50 values for fatty acid inhibition of EqBChE were:
    • Arachidonic acid (AA): 45.49 μM
    • Alpha-linolenic acid (ALA): 8.465 μM
    • Linoleic acid (LA): 1556 μM
    • Oleic acid (OA): 56.57 μM
  • The corresponding Ki values were:
    • AA: 63.92 μM
    • ALA: 11.46 μM
    • LA: 1800 μM
    • OA: 15.24 μM
  • Among these, alpha-linolenic acid (ALA) exhibited the strongest inhibition (lowest IC50 and Ki), indicating the highest affinity for EqBChE.
  • Kinetic analysis revealed:
    • ALA caused mixed inhibition, meaning it can bind both to the enzyme and the enzyme-substrate complex.
    • AA, LA, and OA showed non-competitive inhibition, a special case of mixed inhibition where inhibitor binds primarily to the enzyme at an allosteric site rather than the active site.
  • Molecular docking suggested that fatty acids bind:
    • Directly to the active site of EqBChE.
    • At predicted allosteric binding sites, consistent with the type of inhibition observed.

Significance and Conclusion

  • This study experimentally confirms that unsaturated fatty acids can inhibit EqBChE activity at micromolar concentrations.
  • The inhibition involves binding not only to the active catalytic site but also to allosteric sites on the enzyme.
  • The findings support the hypothesis that cholinesterases like BChE are functionally linked with lipid metabolism, possibly regulating or being regulated by the presence of specific fatty acids.
  • Understanding this interaction could have implications for physiological processes where lipid metabolism and cholinesterase activity intersect, such as in drug metabolism or neurological function.

Cite This Article

APA
Akay MB, Sener K, Sari S, Bodur E. (2025). Inhibitor Action of Unsaturated Fatty Acids on Equine Serum Butyrylcholinesterase. Protein J, 44(3), 271-282. https://doi.org/10.1007/s10930-025-10259-8

Publication

The protein journal
ISSN: 1875-8355
NlmUniqueID: 101212092
Country: Netherlands
Language: English
Volume: 44
Issue: 3
Pages: 271-282

Researcher Affiliations

Akay, Mehmet Berk
  • Faculty of Medicine, Department of Medical Biochemistry, Hacettepe University, Ankara, 06100, Turkey.
Sener, Kubra
  • Faculty of Science, Department of Biology, Gazi University, Ankara, 06500, Turkey.
Sari, Suat
  • Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Hacettepe University, Ankara, 06100, Turkey.
Bodur, Ebru
  • Faculty of Medicine, Department of Medical Biochemistry, Hacettepe University, Ankara, 06100, Turkey. ebodur@hacettepe.edu.tr.

MeSH Terms

  • Horses
  • Butyrylcholinesterase / blood
  • Butyrylcholinesterase / chemistry
  • Butyrylcholinesterase / metabolism
  • Animals
  • Cholinesterase Inhibitors / chemistry
  • Cholinesterase Inhibitors / pharmacology
  • Molecular Docking Simulation
  • Fatty Acids, Unsaturated / chemistry
  • Fatty Acids, Unsaturated / pharmacology
  • Kinetics
  • Catalytic Domain

Grant Funding

  • THD-2023-20014 / Hacettepe University, Turkey

Conflict of Interest Statement

Declarations. Competing Interests: The authors declare no competing interests.

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Citations

This article has been cited 2 times.
  1. Akay MB, Sonmez G, Sari S, Solak HS, Bodur E. Expanding cholinesterase function: kinetic and structural evidence for hydrolysis of long-chain fatty-acid esters.. Naunyn Schmiedebergs Arch Pharmacol 2026 Jan 23;.
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  2. Hajimohammadi S, Lockridge O, Masson P. New views on physiological functions and regulation of butyrylcholinesterase and potential therapeutic interventions.. Front Mol Biosci 2025;12:1625318.
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