Molecular Dynamics Simulation Of Interaction Mechanism Between Plasma And Protein At Atmospheric Pressure

Cold atmospheric plasma(CAP)can directly act on living biological tissues,with the advantages of low energy consumption,easily using,high safety,and little tissue stimulation,etc.It has a wide range of research and application prospects in agricultural and medical fields.At the present stage,atmospheric low temperature plasma has been applied in many directions in the field of plasma medicine,and can be in direct contact with biological tissues.However,the reaction mechanism of plasma active particles and biological macromolecules has not been explained clearly.Protein is an important living substance of organisms.It is very important to study the reaction mechanism between active plasma particles and proteins.In the field of plasma medicine,the plasma treatment of cancer is of particular concern.Experiments have found that plasma treatment of cancer cells can induce apoptosis and inhibit proliferation of cancer cells.Among them,researchers have done a lot of research on the effect of low-temperature plasma at atmospheric pressure on malignant melanoma(MM)cells.Experiments have shown that low temperature plasma at atmospheric pressure can inhibit the proliferation and diffusion of melanoma cells and induce the apoptosis of melanoma cells.Recently,researchers also found a close relationship between melanoma inhibitory activity(MIA)protein and melanoma spread,which has confirmed the specificity of MIA protein as a tumor marker of malignant melanoma.Simulation,with the help of molecular dynamics(MD)and ReaxFF,of plasma ROS(reactive oxygen species)active particles and protein(MIA)molecules reveals the reaction and explain protein molecules damage by the activity of plasma particles at the molecular and atomic level.Simulation not only explains the reaction mechanism of plasma particles with protein,but also explained the inhibition of melanoma diffusion process by plasma at the micro level.Research also helps to provide support for the study of the mechanism of cancer inhibition by plasma.The main content of the article includes the following aspects:(1)The development processes of plasma and plasma technology are reviewed in this paper.This paper introduces the active ingredients of plasma,plasma generating device and influence of biological macromolecules(including proteins,lipids,nucleic acids)by plasma,also introduces the molecular dynamics simulation,the reactive force field and the application modules,etc.(2)The molecular dynamics simulation method was used to simulate the reactions of different types and concentrations of plasma ROS active particles(including ground-state oxygen atoms,hydroxyl groups,ozone molecules)and protein molecule(MIA protein molecule).Simulation results show that the dehydrogenation reaction between of protein molecules by ROS active particles is mainly conducted,and dehydrogenation reaction may produce carbon-carbon double bonds and oxygen-containing functional groups.During the dehydrogenation reaction,the structure and nature of the amino acid residues of the protein have been changed,which has a certain impact on the activity of MIA molecule.If the dehydrogenation reaction occurs on the key amino acid molecule,it will have a serious impact on the dimerization of MIA and eventually affect the spread of melanoma.If the ROS active particle concentration increases,the protein molecule peptide chain rupture response may occur,and the results show that the higher ROS particle concentration,the more intense the dehydrogenation reaction,the greater the probability of damage of amino acid residues,peptides and the higher the probability of fracture,the more serious MIA protein activity and the influence of the diffusion process of melanoma would be.On the basis of studying the reaction between plasma active particle and MIA protein,the reaction between active particles and amino acid molecule was also studied,which not only verified the reaction between MIA protein and active particles,but also provided basic research for the reaction between plasma active particle and other proteins.(3)In the research,on the basis of the reaction of plasma particles with protein,the reaction mechanism of plasma particles and fatty acid molecules is also studied.Fatty acid molecules is important components of human keratin,and plasma particles also need go through the skin cutin layer to come into contact with MIA protein molecules,so revealing the active particles effects on lipid microscopic organisms reaction mechanism is of great significance.The reaction between ROS active particles and skin cuticle fatty acid(linolenic acid)molecules at different concentrations was simulated by reaction molecular dynamics,and the reaction process between ROS active particles and cuticle fatty acid molecules was explained at the micro level.As a control,the reactions of three major fatty acid molecules of olive oil with ROS active particles were simulated.The simulation results showed that dehydrogenation was the main reaction between ROS active particles and fatty acid molecules.The higher the concentration of ROS active particles,the more intense the dehydrogenation reaction would be.The result of dehydrogenation reaction might be individual hydrogen atoms or create new functional groups,such as alcohol group and aldehyde group.During the reaction of fatty acid molecules with high concentration of ROS active particles,a small amount of fatty acid molecules were decarboxylated to form carbon dioxide and to break the carbon chain.