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.
|Exposure duration||continuous for 3 h|
|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.|
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."