Questo sito utilizza cookie di terze parti per inviarti pubblicità in linea con le tue preferenze. Se vuoi saperne di più clicca QUI 
Chiudendo questo banner, scorrendo questa pagina, cliccando su un link o proseguendo la navigazione in altra maniera, acconsenti all'uso dei cookie. OK

Effects of microwaves (0.9-2 GHz) on metalloproteins and electron-transfer reactions

This work is the main part of more extensive research project which plans to establish a direct relationship between mobile phone emission and biological effects. As explained in introduction (cfr sections 1.4), a real biological system is a very complicated and synergic ensemble of different interacting substructures. We have already explained why we decided to work at very basic molecular level, supposing that any possible damages can be propagated to more complex systems. In particular we focused our studies on metallo-proteins and metallo-enzymes which catalyzed electron transfer reactions. At beginning of these studies we carried out some experiments using a commercial mobile phone as a radiation source and we found structural and kinetic effects induced on several enzymes. In particular, we have reported the results obtained on the lactoperoxidase, which changes structure and activity as a consequence of mobile phone irradiation. Given the variability of mobile phone as a radiation source (cfr section 1.5) we decided to use a certified controlled exposure system which emits at 902 MHz and a lower power than mobile phone. We carried out studies on several different iron storage and binding proteins, peroxidases, cytochrome c and copper enzymes.
Furthermore we carried out kinetic experiments on non-enzymatic electron transfer reactions to put in evidence as and how microwaves can interfere with their reaction mechanisms. We found experimental evidences which show MWs irradiation alters structure and activity of these systems. We also demonstrate that, at the frequencies and power we used, microwaves cannot induce instantaneous thermal effects. Therefore all the effects we found are ascribable exclusively to the microwaves-sample interaction.
Finally we carried out some experiments to compare the effect induced by mobile phone and by the controlled exposure system. In general we never found a system altered by mobile phone and not by wave guide and vice versa, so the effects seem due to frequency irradiating (not to power used), in particular at 900 MHz.
We collected experimental data which demonstrate that microwaves affect structure and activity of biological macromolecules. Finally, we formulated several hypothesis about a possible mechanism of interaction. We propose that microwaves probably interfere with paramagnetic species, such as transition metals and/or radicalic intermediates and with the overall dipole momentum of proteins or of the substructures, such as α-helices. It is in fact, reasonable to think microwaves having frequency about 1 GHz can give resonance phenomenon interacting with proteins, since their skeletal movements are ns order, and with reactions with kinetic constants of similar frequency. It is also possible microwaves affect the hydration water structure which is strongly bounded in the protein structure. Nowadays we believe that our experimental data are consistent and they could constitute a solid basis on which to build a model of interaction which anyway should be corroborated by means of further theoretical support.

Mostra/Nascondi contenuto.
1. INTRODUCTION 1.1 The electromagnetic spectrum The electromagnetic (EM) spectrum is the range of all possible electromagnetic radiations. Conventionally the EM is divided into several ranges according to the peculiar wavelengths, as shown in Figure 1.1.1. Figure 1.1.1 The electromagnetic spectrum. RF and MW were highlighted, in particular mobile phone frequency The electromagnetic fields are generally classified in ionizing and non-ionizing radiations (cfr. Figure 1.1.1). An ionizing radiation has energy enough to remove bound electrons from the external shell of an atom, effectively causing the atom ionization. Conversely a non-ionizing radiation has not this ability. Until recently it has been thought that non-ionizing radiations had only a thermal effect on living being; however, in the last few years several researches have disproven this belief, as it will be explained in the next sections. In this work we show how non-ionizing radiation, in the 1

Tesi di Dottorato

Dipartimento: Chimica

Autore: Roberta De Carolis Contatta »

Composta da 120 pagine.


Questa tesi ha raggiunto 95 click dal 19/11/2010.

Disponibile in PDF, la consultazione è esclusivamente in formato digitale.