Study type: Medical/biological study (experimental study)

Non-thermal effects of electromagnetic fields at mobile phone frequency on the refolding of an intracellular protein: myoglobin med./bio.

By: Mancinelli F, Caraglia M, Abbruzzese A, d'Ambrosio G, Massa R, Bismuto E
Published in: J Cell Biochem 2004; 93 (1): 188-196
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Aim of study (acc. to author)

To study possible nonthermal effects of microwaves on the refolding of myoglobin as model protein: 1) The refolding kinetics of the heme binding site, and 2) the conformational dynamics of acidic myoglobin molecules by intrinsic fluorescence decay at pH 3.0 (the lowering of pH causes the destruction of the hydrophobic binding site of the heme) in exposed and non-exposed samples were investigated.

Background/further details

Myoglobin was selected because it can be considered a good model to study protein interactions with microwave electromagnetic fields for its well-known high-resolution crystallographic structure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.95 GHz
Modulation type: CW
Exposure duration: continuous for 3 h

Exposure 1

Main characteristics
Frequency 1.95 GHz
Type
Exposure duration continuous for 3 h
Modulation
Modulation type CW
Exposure setup
Exposure source
  • waveguide
  • 110 x 55 x 500 mm, surrounded by a thermostated water jacket
Setup The sample (3 ml of solution) in a polystyrene cuvette (10 x 10 x 35 mm) was placed vertically in the waveguide where the incident E field (vertical) was maximum.
Sham exposure A sham exposure was conducted.
Additional info The sample temperature at the beginning was 25 ± 0.1°C, it increased to 30 ± 0.1°C in about 30 min, and it remained at that value for the rest of the exposure period. In order to provide a "sham" exposure for each experiment, a cuvette was placed into a thermal bath reproducing the same temperature time course as in the RF exposed sample.
Parameters
Measurand Value Type Method Mass Remarks
SAR 51 mW/g mean determined by power loss - ± 1 mW/g
Measurement and calculation details

Power meters and sensors were used to measure the incident, reflected, and transmitted powers for determining the average SAR. The SAR, its standard deviation, and relative dispersion were also calculated as described in [Bismuto et al., 2003].

Reference articles

  • Bismuto E et al. (2003): Are the conformational dynamics and the ligand binding properties of myoglobin affected by exposure to microwave radiation?

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The kinetics of irradiated samples appear to be slowered by microwave electromagnetic field action. In the presence of microwave electromagnetic fields the propensity of protein molecules to populate specific conformational substates seems to be affected.
Changes in the structural fluctuation caused by microwave perturbation can affect differently the aggregation process that occurs competitively during the protein folding, so representing a potential risk for protein "misfolding."

Study character:

Study funded by

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