Reverse-micelle model: pH, electromagnetic field and inhibitor enzyme interaction.

Abstract

The reverse micelle is one of many models thought to have properties more nearly resembling the biological cellular environment, than does the traditional dilute-solution biochemical reaction system. In order to evaluate the results of EMF perturbation of enzyme-catalyzed reactions, the description of the AOT reverse-micelle model, with respect to its internal pH, effect of chemical inhibitors, temperature, and electromagnetic-field perturbation has herein been extended. Acetylcholinesterase and NADPH cytochrome-P450 reductase, reacting within the AOT reverse-micelle, exhibit a temperature vs. activity profile equivalent to the same reaction in a buffered dilute-solution environment. In reverse micelles, some inhibitors of AChE (propidium, and d-tubocurarine) have much less effect upon indophenol-acetate hydrolysis than they do in a dilute solution environment. Other inhibitors act in the same manner within the structured environment of the reverse micelle as in the conventional dilute solution reaction model. These differences are explicable in terms of mechanism of action of the individual inhibitors. Perturbation by low-intensity microwave fields has a similar inhibitory effect upon dilute-solution reactions, as those in the 'low-water-activity' environment of the reverse micelle. However, the interactions between physical and chemical perturbants are differently limited by the structure of the aqueous phase of the reverse micelle. pH of the 'internal' reverse-micelle environment is a function of the availability of H-ions supplied by system components. Use of indicator dyes show that the low-molarity buffers which are compatible with reverse-micelle stability, are often insufficient to maintain a constant pH. Too, in the reverse micelle, reaction rate, for proton yielding reactions, is dramatically greater than the rate of the same reaction in dilute solution at the same acidic pH.

AI evidence extraction

Main findings

In an AOT reverse-micelle model, low-intensity microwave-field perturbation produced a similar inhibitory effect on enzyme reactions as observed in dilute-solution reactions, though interactions between physical (microwave) and chemical perturbants were differently limited by the reverse-micelle aqueous-phase structure. Some acetylcholinesterase inhibitors had much less effect in reverse micelles than in dilute solution, while others acted similarly in both environments; internal pH control in reverse micelles was described as variable and buffer-limited.

Outcomes measured

• Enzyme-catalyzed reaction activity (acetylcholinesterase; NADPH cytochrome-P450 reductase)
• Inhibitor effects on acetylcholinesterase (e.g., propidium, d-tubocurarine)
• pH behavior in AOT reverse-micelle environment

Limitations

• No microwave frequency, exposure metric (e.g., SAR), or duration reported in the abstract
• In vitro/model system (reverse micelles) rather than whole organisms or human populations
• No quantitative effect sizes or statistical details provided in the abstract
• Scope includes multiple perturbations (pH, temperature, chemical inhibitors) which may complicate attribution to EMF alone

{
    "study_type": "other",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Enzyme-catalyzed reaction activity (acetylcholinesterase; NADPH cytochrome-P450 reductase)",
        "Inhibitor effects on acetylcholinesterase (e.g., propidium, d-tubocurarine)",
        "pH behavior in AOT reverse-micelle environment"
    ],
    "main_findings": "In an AOT reverse-micelle model, low-intensity microwave-field perturbation produced a similar inhibitory effect on enzyme reactions as observed in dilute-solution reactions, though interactions between physical (microwave) and chemical perturbants were differently limited by the reverse-micelle aqueous-phase structure. Some acetylcholinesterase inhibitors had much less effect in reverse micelles than in dilute solution, while others acted similarly in both environments; internal pH control in reverse micelles was described as variable and buffer-limited.",
    "effect_direction": "harm",
    "limitations": [
        "No microwave frequency, exposure metric (e.g., SAR), or duration reported in the abstract",
        "In vitro/model system (reverse micelles) rather than whole organisms or human populations",
        "No quantitative effect sizes or statistical details provided in the abstract",
        "Scope includes multiple perturbations (pH, temperature, chemical inhibitors) which may complicate attribution to EMF alone"
    ],
    "evidence_strength": "very_low",
    "confidence": 0.66000000000000003108624468950438313186168670654296875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "reverse micelle",
        "AOT",
        "acetylcholinesterase",
        "NADPH cytochrome-P450 reductase",
        "microwave fields",
        "low-intensity",
        "enzyme inhibition",
        "pH",
        "chemical inhibitors",
        "indophenol-acetate hydrolysis"
    ],
    "suggested_hubs": []
}

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