研究のタイプ: 医学／生物学の研究 (experimental study)

[カゴ状タンパク質の分子動態及び鉄取り込みに無線周波磁界は影響する] med./bio.

Radio frequency magnetic field effects on molecular dynamics and iron uptake in cage proteins

著者: Cespedes O, Inomoto O, Kai S, Nibu Y, Yamaguchi T, Sakamoto N, Akune T, Inoue M, Kiss T, Ueno S
掲載誌: Bioelectromagnetics 2010; 31 (4): 311-317
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この研究は、野生種のウマの脾臓のフェリチン（室温超常磁性を有する天然のフェリハイドライト・ナノ粒子をもつ）の性質を調べ、それに対する無線周波電磁界の影響を調べた。まず、このナノ粒子の低磁界中での磁化率とネール緩和時間を測定し、報告している。次に、無線周波磁界にばく露した場合、超常磁性ナノ粒子は磁化と印加磁界との時間差によって内部エネルギーを増加させ、このエネルギーは、周囲のペプチドのかご状構造へと拡散していき、分子動態及びプロテイン機能を変化させると著者は考えて、ラマン分光法で計測した結果、1 MHz、30 μTの磁界下で低エネルギー振動状態の拡大が確認されたと報告している。また、ばく露終了から2時間の時点でタンパク質の鉄取り込み速度は約20％減少したと述べている。

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研究目的(acc. to editor)

To study the effects of radiofrequency magnetic fields on ferritin and the underlying mechanisms. Additionally, the aim of the study was to determine, whether the effects of such fields as described in a previous study (i.e. decrease in iron chelation following exposure, see Céspedes and Ueno 2009) are due to power dissipation of the ferrihydrite nanoparticles under exposure to the radiofrequency field.

詳細情報

The iron cage protein ferritin is an obvious candidate to study the effects of radiofrequency magnetic fields at the molecular scale, because it has the highest net magnetic moment of all proteins and plays an essential biological role, being present in organisms from bacteria to humans. Ferritin oxidizes the harmful Fe2+ ions and stores them in the cavity, forming a superparamagnetic ferrihydrite nanoparticle with up to 4,500 iron ions. Apoferritin solutions (protein without inner ferrihydrite nanoparticle) were also investigated.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1 MHz
ばく露時間: continuous for 7 h
ばく露2: 50 kHz–2 MHz

ばく露1

主たる特性
周波数 1 MHz
タイプ
  • magnetic field
ばく露時間 continuous for 7 h
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 1 m
ばく露装置の詳細 two sets of coils placed above and below samples; coils 9 cm in diameter and 1 cm in height spaced by 5 cm.
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 30 µT maximum 計算値 - -
Additional parameter details

Magnetic flux densities calculated from electrical current/voltage measurements.

ばく露2

主たる特性
周波数 50 kHz–2 MHz
タイプ
  • magnetic field
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
パラメータ
測定量 値 種別 Method Mass 備考
磁束密度 15 µT maximum 計算値 - -

Reference articles

ばく露を受けた生物:

方法 影響評価項目／測定パラメータ／方法

研究対象とした生物試料:
調査の時期:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム（著者による）

The data showed that exposure to a radiofrequency magnetic field affected the ability of native ferritin to uptake iron. However, the radiofrequency magnetic field had no effect on ferritin without inner superparamagnetic nanoparticle (i.e. apoferritin).
The superparamagnetic nanoparticles inside of ferritin increase their internal energy when exposed to radiofrequency magnetic fields due to the lag between magnetization and applied field. The energy is dissipated to the surrounding "protein cage", altering the molecular dynamics and functioning of the protein. This leads to an increased population of low energy vibrational states under a magnetic field of 30 µT at 1 MHz (as measured via Raman spectroscopy). After 2 h of exposure, the proteins have a reduced iron intake rate of about 20%.
In conclusion, the data open a new path for the study of non-thermal bioeffects of radiofrequency magnetic fields at the molecular scale. The authors hypothesize that the effect of the radiofrequency magnetic field on ferritin will depend not only on the applied field but also on the magnetic properties of the ferrihydrite nanoparticle inside ferritin.

研究の種別:

研究助成

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