1 Institute of Biomedical Chemistry, Moscow, Russia
2 Joint Institute for High Temperatures of the Russian Academy of Sciences, Moscow, Russia
3 Foundation of Perspective Technologies and Novations, Moscow, Russia
4 Moscow State Academy of Veterinary Medicine and Biotechnology Named after Skryabin, Moscow, Russia
5 Faculty of Computational Mathematics and Cybernetics, Moscow State University, Moscow, Russia
The effect of a high-voltage discharge in a helicoidal structure on the adsorption properties of an enzyme on mica has been studied with the example of horseradish peroxidase (HRP). The discharge was generated at the expense of a sparkover in a 3 mm gap between two electrodes, to which a 10 kV, 50 Hz AC voltage was applied. The electrodes were connected to a twisted pair, which was wound onto a cone, forming the helicoidal structure. The incubation of the enzyme solution near the top of the helicoidal structure has been found to cause an increase in the degree of aggregation of HRP adsorbed on mica in comparison with the control HRP sample. The results obtained should be taken into account in studies of enzymes using biosensors with helicoidal structures as heating elements, as well as in refining models describing effects of low-frequency alternating current, flowing through helicoidal structures, on proteins and biological objects.
Keywords: atomic force microscopy; helicoidal structure; electric discharge; electromagnetic field; protein aggregation; enzyme adsorption
Recently, the study of protein aggregation has attracted great interest owing to the involvement of protein aggregates in maintaining optimal body functioning. Such diseases as Alzheimer’s [1,2,3], Parkinson’s , cardiovascular , and oncological ones  are known to be associated with increased aggregation of proteins. A positive example of controlled protein aggregation is the dimerization of myeloperoxidase, which provides normal functioning of the body . Certain amyloid proteins—for instance, FXR1 protein—are also necessary for optimal brain functioning .
Electromagnetic fields are known to have a significant impact on the human body, causing various pathologies [7,8,9,10]. Technological development leads to a steady increase in the level of electromagnetic background induced by power lines operated at 50 Hz industrial frequency. Such electromagnetic fields can affect the body, influencing blood rheology  or blood pressure . When high-voltage lines are grounded, or when lightning strikes an electrical power line, significant electromagnetic fields are induced. Therefore, studying the effect of discharges from high-voltage sources, connected to various current-carrying structures, on biological objects is an important task. The circuits containing twisted-pair wires are the most interesting ones from the viewpoint of the organization of current-carrying signals and power circuits. The twisted pair represents a pair of conductors twisted together  in order to suppress losses in the transmission of electrical signals. Although the twisted pair is designed to provide suppression of losses, it normally emits electromagnetic waves. It is known that even weak alternating electromagnetic fields of non-thermal power can change the properties of enzymes . As regards alternating electromagnetic fields of low frequency, their action on enzymes can lead to either an increase or a decrease in the enzymatic activity, depending on the enzyme and the field parameters. Several membrane-associated enzymes (namely, alkaline phosphatase, acetylcholinesterase from blood cell membranes, acetylcholinesterase from synaptosomes, phosphoglycerate kinase, and adenylate kinase) were reported to lose their activity under the influence of a 75 Hz electromagnetic field, while other enzymes (CaATPase, Na/K ATPase, and succinic dehydrogenase) were found to be virtually insensitive to fields of this frequency . A 20 Hz electromagnetic field was found to have a very significant stimulating effect on cAMP-dependent protein kinase . As regards horseradish peroxidase (HRP) enzyme, its catalytic efficiency decreased nearly twofold after its exposure to a 50 Hz electromagnetic field, while being unaffected by a 100 Hz field .
Considering the impact of radiofrequency electromagnetic fields, radiofrequency heating (27.12 MHz 6 kW) was reported to have quite the opposite effect on the enzymatic activity of HRP . While the treatment at 50 °C slightly increased the enzymatic activity, it significantly decreased after the heating at higher (70 °C and 90 °C) temperatures . The exposure of HRP to either a 13.56 MHz, 915 MHz, or 2.45 GHz electromagnetic field was reported to have no nonthermal effect on HRP . On the contrary, microwave treatment was reported to cause very significant inactivation of HRP , red beet peroxidase, and polyphenoloxidase .
In this work, the influence of a high-voltage discharge in a helicoidal structure, based on a twisted pair, on the properties of enzymes has been studied. As a helicoidal element, a twisted pair, wound onto a conical surface, has been employed. The discharge current flowed through a helicoidal structure of copper twisted pair wires during a discharge in the air gap between the electrodes from a high-voltage AC power supply (10 kV, 50 Hz). Similar discharge devices are used in voltage limiters . As a model object, HRP has been used, since it is comprehensively characterized in the literature. It is known that HRP exists in solution in the form of monomers and aggregates [23,24]. Atomic force microscopy (AFM) has been employed to study the influence of a high-voltage discharge on the enzyme. AFM allows one to study the influence of electromagnetic fields on enzyme aggregation at the level of single molecules [14,23,25,26], revealing even subtle effects , when the electromagnetic field intensity is at the background level [23,26].
Our AFM study has revealed that the incubation of HRP solution near the top of a helicoidal structure upon flowing of a discharge current through this structure leads to an increased aggregation of the enzyme on a mica surface.
The results of our study can be used in the development of biosensors employing helicoidal conductive structures operating at industrial AC frequency, and for designing and refining models of the influence of alternating electromagnetic fields of various configurations on biological objects.
Ivanov, Y.D.; Tatur, V.Y.; Shumov, I.D.; Kozlov, A.F.; Valueva, A.A.; Ivanova, I.A.; Ershova, M.O.; Ivanova, N.D.; Stepanov, I.N.; Lukyanitsa, A.A.; Ziborov, V.S. The Influence of a High-Voltage Discharge in a Helicoidal Twisted-Pair Structure on Enzyme Adsorption. Electronics 2022, 11, 3276. https://doi.org/10.3390/electronics11203276