Real‐time assessment of possible electromagnetic‐field‐induced changes in protein conformation and thermal stability

Abstract

Previous studies on possible interactions of radiofrequency electromagnetic fields (RF EMFs) with proteins have suggested that RF EMFs might affect protein structure and folding kinetics. In this study, the isolated thermosensor protein GrpE of the Hsp70 chaperone system of Escherichia coli was exposed to EMFs of various frequencies and field strengths under strictly controlled conditions. Circular dichroism spectroscopy was used to monitor possible structural changes. Simultaneously, temperature was recorded at each point of observation. The coiled-coil part of GrpE has been reported to undergo a well-defined and fully reversible folding/unfolding transition, thus facilitating the differentiation between thermal and non-thermal effects of RF EMFs. Any direct effect of EMF on the conformation and/or stability would result in a shift of the conformational equilibrium of the protein at a given temperature. Possible immediate (t ≤ 0.1 s) and delayed (t ≥ 30 s) effects of RF EMFs were investigated with sinusoidal signals of 0.1, 1.0, and 1.9 GHz at various field strengths up to 5.0 kV/m and with GSM signals at 0.3 kV/m in the protein solution. Taking the overall uncertainty of the experimental system into account, possible RF EMF-induced shifts in the conformational equilibrium of less than 1% of its total range might have been detected. The results obtained with the different experimental protocols indicate, however, that the conformational equilibrium of GrpE is insensitive to electromagnetic fields in the tested range of frequency and field strength.

Evaluation of the effects of weak oscillating magnetic fields applied during freezing on systems of different complexity

“…Slow freezing protocols combined with fast thawing rates and the use of cryoprotectants such as serum albumin are frequently used to improve LDH viability, but with moderate results [9]. Different authors have shown that the application of high-frequency electromagnetic fields at room temperature has non-thermal effects on macromolecules, proteins and enzymes [10][11][12][13][14] and, in particular, Vojisavljevic, Pirogova [11,15] showed that LDH activity could be modulated by electromagnetic waves in the microwave frequency range. However, to the best of our knowledge, no data exist on the effect of low-frequency OMFs on LDH activity.…”