Molecular Dynamics Research of Spatial Orientation and Kinetic Energy of Active Site Collision of Carnosine under Weak Microwave Irradiation

Abstract

Molecular Dynamics Research of Spatial Orientation and Kinetic Energy of Active Site Collision of Carnosine under Weak Microwave Irradiation Gou D, Huang K, Liu Y, Shi H, Wu Z. Molecular Dynamics Research of Spatial Orientation and Kinetic Energy of Active Site Collision of Carnosine under Weak Microwave Irradiation. J Phys Chem B. 2022 Sep 22. doi: 10.1021/acs.jpcb.2c03930. Abstract The molecular mechanism of the microwave nonthermal effect is still not clear. This work investigated the spatial orientation and kinetic energy of active site collision of carnosine, a natural bioactive dipeptide, under the weak microwave irradiation using the molecular dynamics simulation. Our results showed the influences of the temperature, microwave intensity, microwave frequency, and microwave polarization mode (linear polarization and circular polarization) on the spatial orientation and kinetic energy of active site collision of carnosine. First, under the constant intensity and frequency of linear polarization microwave irradiation, the increment of the collision probability between the 6N atom of carnosine and the 28H atom of the other carnosine at effective space angle decreases from 85.0% to 3.5% with increasing temperature. Second, with the increase of microwave intensity, the change of spatial orientation and kinetic energy becomes more and more significant. However, the change of circular polarization microwaves on the spatial orientation and kinetic energy of collision is weaker than that of linear polarization. Third, under the constant intensity of linear polarization microwave irradiation, the collision probability between the 6N atom and the 28H atom at effective space angle decreases from 70.2% to 14.7% with increasing frequency. Finally, under the microwave polarization, the spatial orientation and kinetic energy of molecular collision are changed, which is summarized as the microwave postpolarization effect (MWPPE). The dependence of MWPPE on temperature, microwave intensity, microwave frequency, and polarization mode is very complicated. In the end, this effect can provide a new insight into the molecular mechanism of the microwave nonthermal effect. pubmed.ncbi.nlm.nih.gov Conclusions The goal of this investigation is to study the spatial orientation and kinetic energy of active site collision of carnosine under weak microwave irradiation. In this work, the effects of temperature, microwave intensity, microwave frequency, and microwave polarization mode (linear polarization and circular polarization) on carnosine active site collision were inves- tigated using molecular dynamics simulation. For the active site collision of carnosine, we mainly targeted the collision between the 6N atom of carnosine and the 28H atom of the other carnosine and the collision between the 6N atom of carnosine and the 30H atom of the other carnosine. The influence of weak microwave irradiation on active site collision of carnosine is affected by many factors mentioned above. First, for linear polarization microwave radiation with the constant microwave intensity and frequency, the increment of total collision number decreases with the increase of temperature. Similarly, the increment of collision probability at specific spatial angle also decreases, and the fraction of high-energy collisions also decreases. This confirms that the molecular thermal motion becomes more intense as the temperature rises, which weakens the polarization effect of microwaves. Second, with the increase of microwave intensity, the influence of spatial orientation and kinetic energy becomes more and more significant. However, the effect of circular polarization on the spatial direction and kinetic energy of collision is weaker than that of linear polarization. This shows that, compared with linear polarization microwaves, the direction of the electric field in circular polarization changes faster, and the orientation effect of dipole molecules is obviously weaker than that of linear polarization. Third, under the constant intensity of linear polarization microwave radiation, with the increase of microwave frequency, the influence of spatial direction and kinetic energy becomes weaker and weaker. This proves that the orientation effect of molecules following the direction of electric field decreases with increasing microwave frequency. Finally, we determine the effect of the microwave radiation on the spatial orientation and kinetic energy of collision. The higher intensity is the more obvious the effect will be. However, the higher temperature, the higher frequency, and circular polarization will weaken the effect. On the basis of the collision theory, we further verify the total effect of weak microwave irradiation on spatial orientation and kinetic energy of active site collision by analyzing the effective molecular collision number and introduce electromagnetic action factor. The conclusion is consistent with that described above. At last, the effect of the weak microwaves on the spatial orientation and kinetic energy of active site collision is called the microwave postpolarization effect (MWPPE). The MWPPE provides a new way to understand the molecular mechanism of the microwave nonthermal effect. In addition, it can also provide useful reference for designing experiments to verify the nonthermal effect of weak microwave irradiation.

AI evidence extraction

Main findings

Using molecular dynamics simulations, the study reports that weak microwave irradiation can alter the spatial orientation and kinetic energy of carnosine active-site collisions, with effects depending on temperature, microwave intensity, frequency, and polarization mode. Reported changes were stronger with higher intensity, weaker at higher temperature and higher frequency, and weaker for circular versus linear polarization.

Outcomes measured

• Spatial orientation of carnosine during molecular collisions
• Kinetic energy of active-site collisions (e.g., 6N–28H, 6N–30H)
• Collision probability/number at effective spatial angles
• Proposed 'microwave postpolarization effect' (MWPPE)

Limitations

• Simulation (molecular dynamics) study rather than measurements in biological systems
• Exposure parameters (e.g., exact frequency values, intensity metrics, SAR) are not fully specified in the provided abstract text
• Outcomes are molecular-collision metrics and a proposed mechanism, not health or clinical endpoints
• Generalizability to real-world exposures and complex biological environments is not established in the provided text

{
    "publication_year": null,
    "study_type": "other",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "Spatial orientation of carnosine during molecular collisions",
        "Kinetic energy of active-site collisions (e.g., 6N–28H, 6N–30H)",
        "Collision probability/number at effective spatial angles",
        "Proposed 'microwave postpolarization effect' (MWPPE)"
    ],
    "main_findings": "Using molecular dynamics simulations, the study reports that weak microwave irradiation can alter the spatial orientation and kinetic energy of carnosine active-site collisions, with effects depending on temperature, microwave intensity, frequency, and polarization mode. Reported changes were stronger with higher intensity, weaker at higher temperature and higher frequency, and weaker for circular versus linear polarization.",
    "effect_direction": "mixed",
    "limitations": [
        "Simulation (molecular dynamics) study rather than measurements in biological systems",
        "Exposure parameters (e.g., exact frequency values, intensity metrics, SAR) are not fully specified in the provided abstract text",
        "Outcomes are molecular-collision metrics and a proposed mechanism, not health or clinical endpoints",
        "Generalizability to real-world exposures and complex biological environments is not established in the provided text"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "unknown",
    "stance": "neutral",
    "stance_confidence": 0.61999999999999999555910790149937383830547332763671875,
    "summary": "This molecular dynamics simulation study examined how weak microwave irradiation affects the spatial orientation and kinetic energy of carnosine active-site collisions. The authors report that collision orientation/energy changes depend on temperature, microwave intensity, frequency, and polarization, with stronger effects at higher intensity and weaker effects at higher temperature, higher frequency, and with circular polarization. They summarize these observations as a proposed “microwave postpolarization effect” (MWPPE) intended to inform hypotheses about nonthermal microwave mechanisms.",
    "key_points": [
        "The work uses molecular dynamics simulation to study carnosine under weak microwave irradiation.",
        "Outcomes focus on collision probability/number and kinetic energy for specific atom-pair collisions (e.g., 6N–28H and 6N–30H).",
        "With constant intensity and frequency (linear polarization), the reported increment in collision probability at an effective angle decreases as temperature increases.",
        "Increasing microwave intensity is reported to make changes in spatial orientation and kinetic energy more pronounced.",
        "Circular polarization is reported to have weaker effects on orientation and collision energy than linear polarization.",
        "With constant intensity (linear polarization), increasing microwave frequency is reported to weaken the orientation/kinetic-energy effects.",
        "The authors label the observed phenomenon the microwave postpolarization effect (MWPPE) and suggest it may relate to nonthermal mechanisms."
    ],
    "categories": [
        "Mechanisms",
        "Microwave/RF",
        "In Silico Modeling"
    ],
    "tags": [
        "Molecular Dynamics",
        "Microwave Irradiation",
        "Nonthermal Effects",
        "Carnosine",
        "Polarization",
        "Collision Probability",
        "Kinetic Energy",
        "Frequency Dependence",
        "Temperature Dependence",
        "Mechanistic Hypothesis"
    ],
    "keywords": [
        "molecular dynamics",
        "weak microwave irradiation",
        "carnosine",
        "spatial orientation",
        "kinetic energy",
        "collision probability",
        "linear polarization",
        "circular polarization",
        "frequency",
        "temperature",
        "microwave postpolarization effect",
        "MWPPE"
    ],
    "suggested_hubs": [],
    "social": {
        "tweet": "Molecular dynamics simulations report that weak microwave irradiation can alter carnosine collision orientation and kinetic energy, with effects depending on intensity, frequency, temperature, and polarization (linear > circular). The authors describe this as a “microwave postpolarization effect” (MWPPE).",
        "facebook": "A molecular dynamics simulation study reports that weak microwave irradiation may change the spatial orientation and kinetic energy of carnosine active-site collisions. The reported effects vary with temperature, intensity, frequency, and polarization mode, and are summarized as a proposed “microwave postpolarization effect” (MWPPE).",
        "linkedin": "This molecular dynamics simulation study examines carnosine under weak microwave irradiation and reports changes in collision orientation and kinetic energy that depend on temperature, intensity, frequency, and polarization (linear stronger than circular). The authors propose a “microwave postpolarization effect” (MWPPE) as a potential nonthermal mechanism hypothesis."
    }
}

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