Study type: Medical/biological study (experimental study)

Non-thermal effects of microwaves on proteins: thermophilic enzymes as model system. med./bio.

Published in: FEBS Lett 1997; 402 (2-3): 102-106

Aim of study (acc. to author)

To discriminate between thermal and non-thermal effects of microwave irradiation on two different thermostable enzymes.

Background/further details

Both enzymes, S-adenosylhomocystein hydrolase and 5'-methylthioadenosin phosphorylase, were purified from the thermophilic microorganism Sulfolobus solfataricus belonging to the Archaea.



Exposure Parameters
Exposure 1: 10.4 GHz
Modulation type: CW
Exposure duration: continuous up to1 h
  • SAR: 1.5 W/g minimum
  • SAR: 3.1 W/g maximum

Exposure 1

Main characteristics
Frequency 10.4 GHz
Exposure duration continuous up to1 h
Modulation type CW
Exposure setup
Exposure source
Chamber water jacketed sample holder, cone-tipped plastic test tube, 300 µl solution
Measurand Value Type Method Mass Remarks
SAR 1.5 W/g minimum calculated - -
SAR 3.1 W/g maximum calculated - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Both enzymes were irreversible inactivated in a time dependent manner due to non-thermal effects of the exposure. The inactivation rate is independent of the enzyme concentration and is related to the energy absorbed. Furthermore it seems that microwaves induce structural changes in protein conformation, as investigated on S-adenosylhomocystein hydrolase by fluorescence and circular dichroism techniques.

Study character:

Study funded by

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