Study type: Medical/biological study (experimental study)

Non-thermal microwave effects on protein dynamics? An X-ray diffraction study on tetragonal lysozyme crystals med./bio.

By: Weissenborn R, Diederichs K, Welte W, Maret G, Gisler T
Published in: Acta Crystallogr D Biol Crystallogr 2005; 61 Pt 2: 163-172
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Aim of study (acc. to author)

To study the structural and dynamical effects of microwave fields on tetragonal single crystals of hen egg-white lysozyme.

Background/further details

Temperature controls were also performed.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 8 GHz
Exposure duration: continuous for 10 min and 4 h
  • power: 0.5 W unspecified (1 W, 2 W and 3 W)

Exposure 1

Main characteristics
Frequency 8 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 10 min and 4 h
Modulation
Modulation type unspecified
Exposure setup
Exposure source
Setup Crystals were located in a 1.25 mm wide gap between the central and the outer conductor where field strength was maximum. The salt solution reservoirs in each coil end of the capillary were located outside the slab-line, hence were not exposed to MMW.
Parameters
Measurand Value Type Method Mass Remarks
power 0.5 W unspecified measured - 1 W, 2 W and 3 W
Additional parameter details

In the 4 hour exposure experiments, crystal 1 was exposed to 1 and 3 W and crystal 2 was exposed to 0.5, 1 and 2 W.

Measurement and calculation details

A power meter was used for measurements.

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)

High microwave power levels mainly led to increased, but largely recoverable, lattice defects owing to the evaporation of crystal water. At lower microwave power levels, the presence of the microwave field resulted in localized reproducible changes in the mean-square displacements (B factors).
The average B factor was found to increase with microwave power, consistent with an increase in temperature. However, the B factors of the atoms in a few highly localized sites in the protein showed reproducuble changes upon microwave exposure that are not explained by heating.

Study character:

Study funded by

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