Medical/biological study (experimental study)

Competition between hydrogen bonding and protein aggregation in neuronal-like cells under exposure to 50 Hz magnetic field med./bio.

By: Calabro E

Published in: Int J Radiat Biol 2016; 92 (7): 395-403

Aim of study (acc. to author)

The effects of exposure of neuronal-like cells to a 50 Hz magnetic field on hydrogen bonds and protein unfolding should be investigated.

Background/further details

Hydrogen bonds play an important role in the formation and stabilization of the protein secondary structure. The delicate balance between many competing bonds can be altered by external stress, changing the structure of the protein.
12 samples were exposed to the magnetic field and the same number was used as the control group.

Endpoint

molecular biosynthesis: hydrogen bonds and protein unfolding in neuronal-like cells

Exposure

- 50 Hz
- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 4 hours	magnetic flux density: 1 mT

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 4 hours

Exposure setup

Exposure source	Helmholtz coils
Chamber	20 cm² culture flasks between coils in incubator with 5% CO₂ and 95% humidified air at 37°C
Setup	two Helmholtz coils with pole pieces of round parallel polar faces; samples were placed at the center of a uniform field area between the coils; each coil had n=124 turns of wire and the coil spacing was assumed to be equal to the coils radius (r=150 mm); during the exposure, no significant increase in the temperature (± 0.1°C) was observed; magnetic field was perpendicular to the culture flask

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1 mT	-	measured	-	-

Additional parameter details

H field within the volume of exposed culture was ± 0.01 mT during exposure; H field from incubators in the area where samples were located was 0.002 mT

Exposed system:

intact cell/cell culture
SH-SY5Y cells (human neuroblastoma cell line)

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: hydrogen bonds and protein unfolding (semi-quantitative detection of asymmetric methyl groups, asymmetric methylene (CH₂) groups, symmetric methylene groups, carbonyl groups, primary amides, secondary amides, alpha helix structures, beta sheet structures; FTIR spectroscopy)

Investigated system:

intact cell/cell culture

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The amount of methylene groups was significantly increased in exposed cells compared to the control group. This might indicate an increase in cellular volume which would correspond to an increase in the surface area and the overall cellular content with fatty acids and phospholipids and a relative increase of methylene groups with respect to methyl groups.
Moreover, a significant decrease in primary amides and a significant increase of beta sheet structures in exposed cells compared to the control group indicated changes in the overall protein conformation state within the cell, which could be due to unfolding of proteins and formation of aggregates.
No significant changes were found for secondary amides.
The authors conclude that exposure to a 50 Hz magnetic field might increase both hydrogen bonds and protein unfolding processes in neuronal-like cells.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

De Ninno A et al. (2014): Influence of magnetic fields on the hydration process of amino acids: Vibrational spectroscopy study of L-phenylalanine and L-glutamine
Calabro E et al. (2013): 50 Hz electromagnetic field produced changes in FTIR spectroscopy associated with mitochondrial transmembrane potential reduction in neuronal-like SH-SY5Y cells
Calabro E et al. (2013): Effects of low intensity static magnetic field on FTIR spectra and ROS production in SH-SY5Y neuronal-like cells
Rebrov VG et al. (2011): Low-frequency magnetic radiation leads to the broadening of valent bonds in protein infrared spectra
Magazu S et al. (2011): Studying the Electromagnetic-Induced Changes of the Secondary Structure of Bovine Serum Albumin and the Bioprotective Effectiveness of Trehalose by Fourier Transform Infrared Spectroscopy
Calabro E et al. (2011): Static and 50 Hz Electromagnetic Fields Effects on Human Neuronal-Like Cells Vibration Bands in the Mid-Infrared Region
Magazu S et al. (2010): FTIR spectroscopy studies on the bioprotective effectiveness of trehalose on human hemoglobin aqueous solutions under 50 Hz electromagnetic field exposure
Ikehara T et al. (2003): Effects of ELF magnetic field on membrane protein structure of living HeLa cells studied by Fourier transform infrared spectroscopy