Study type: Medical/biological study (experimental study)

Non-Thermal effects in the microwave induced unfolding of proteins observed by chaperone binding. med./bio.

Published in: Bioelectromagnetics 2008; 29 (4): 342-330

Aim of study (acc. to author)

To study the effect of microwaves at 2450 MHz on protein (citrate synthase) unfolding.

Background/further details

The protein was exposed to microwaves only, conventional heat (water bath) only and combinations of heat and microwaves.
Unfolding proteins tend to bind to chaperones on their unfolding pathway and this attachment is monitored by surface plasmon resonance.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 10, 15, and 20 s

General information

The protein solution was subjected to microwave exposure, water bath for 5 min at 34 to 82.5 °C, and water bath at 29.5 to 44 °C followed by microwave exposure.

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Exposure duration continuous for 10, 15, and 20 s
Modulation
Modulation type pulsed
Repetition frequency 50 Hz
Additional info

sharply peaked waveform having a peak to average ratio between 3:1 and 8:1 [Matsumoto et al., 2005]

Exposure setup
Exposure source
Chamber A shelf made from high density polyethylene with holes fitting the Eppendorf tubes was located in the microwave oven cavity with a water ballast placed under it in a fixed spot in order to stabilise the field.
Setup The protein solution in an Eppendorf tube of 80 µl volume was placed in the hole determined to have the maximum temperature rise.
Additional info The temperature rise near the end-tip of the Eppendorf tube was measured over a volume of 0.8 mm side length using a fluoroptic probe.
Parameters
Measurand Value Type Method Mass Remarks
SAR 4.85 kW/kg mean - - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The data showed that microwaves caused a significantly higher degree of unfolding than conventional thermal stress for protein solutions heated to the same maximum temperature. The data support the hypothesis that microwaves have a non-thermal effect on protein conformation that could take the form of a direct interaction of the electromagnetic field with the protein or its water of hydration.

Study character:

Study funded by

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