Structural Variations Induced by Temperature Changes in Rotavirus VP6 Protein Immersed in an Electric Field and Their Effects on Epitopes of The Region 300-396

Rotavirus diarrhea is an infectious intestinal disease that causes about 215 thousand deaths annually in infants under five years old. This virus is formed by three layers of concentric proteins that envelop its genome, from which VP6 structural protein is the most conserved among rotavirus serotypes and an excellent vaccine candidate. Recent studies have shown that structural proteins are susceptible to losing their biological function when their conformation is modified by moderate temperature increments, and in the case of VP6, its antigen efficiency decreases. We performed an in silicoanalysis to identify the structural variations in the epitopes 301-315, 357-366, and 376-384 of the rotavirus VP6 protein -in a hydrated medium- when the temperature is increased from 310 K to 322 K. In the latter state, we applied an electric field equivalent to a low energy laser pulse and calculated the fluctuations per amino acid residue. We identified that the region 301-315 has greater flexibility and density of negative electrical charge; nevertheless, at 322 K it experiences a sudden change of secondary structure that could decrease its efficiency as an antigenic determinant. The applied electric field induces electrical neutrality in the region 357-366, whereas in 376-384 inverts the charge, implying that temperature changes in the range 310 K-322 K are a factor that promotes thermoelectric effects in the VP6 protein epitopes in the region 300-396

Theoretical Model to Estimate the Distribution of Radon in Alveolar Membrane Neighborhood

Radon is a naturally occurring radioactive gas which tends to concentrate indoors, easily emanates from the ground into the air, where it disintegrates and emits radioactive particles. It can enter the human body through breathing or ingesting mostly water. When radon inhaled, travels through the respiratory tract to alveoli where the majority is expelled into the environment. Moreover, when ingested in water, it passes into the intestine where it is absorbed and driven from the bloodstream to the lungs; in these organs, due to differences in partial pressures, it is transported to alveoli by simple diffusion process. When radon is not removed, it decays in short-lived solid disintegration products (218Po and 214Po) with high probability of being deposited in biological tissues, causing DNA damage because of the densely ionizing alpha radiation emitted. We propose a semi-empirical, smooth, and continuous pair potential function in order to model the molecular interactions between radon and lung alveolar walls; we use Molecular Dynamics (MD) to determine the gas distribution in an alveolar neighborhood wall, and estimate the quantity thereof it diffuses through the alveolar membrane as a concentration function

Using Green Fluorescent Protein to Correlate Temperature and Fluorescence Intensity into Bacterial Systems

The unique and stunning spectroscopic properties of Green Fluorescent Protein (GFP) from the jellyfish Aequorea victoria, not to mention of its remarkable structural stability, have made it one of the most widely studied and used molecular tool in medicine, biochemistry, and cell biology. Its high fluorescent quantum yield is due to its chromophore, structure responsible of emitting green visible light when excited at 395 nm. Although it is noteworthy that there is enormous available information of the wonderful luminescent properties of GFP, the fact is that there are features and properties unexplored yet, particulary about its capabilities as molecular reporter in several biological processes. In this work, we used recombinant DNA technology to express the protein in bacteria; prepared the bacterial system both in liquid and solid media, and assembled an experimental set to expose those media to a laser beam; thereby we excited the protein chromophore and used emission spectroscopy in order to observe variations in fluorescence when the bacterial system is exposed to different temperatures

Receptor Binding Domain (RBD) Structural Susceptibility in the SARS-CoV-2 Virus Spike Protein Exposed to a Pulsed Electric Field

SARS-CoV-2 is responsible for causing the Coronavirus disease 2019 (COVID-19) pandemic, which has so far infected more than thirty million people and caused almost a million deaths. For this reason, it has been a priority to stop the transmission of the outbreak through preventive measures, such as surface disinfection, and to establish bases for the design of an effective disinfection technique without chemical components. In this study, we performed in silico analysis to identify the conformational alterations of the SARS-CoV-2 Spike Receptor Binding Domain (RBD) caused by the effect of a pulsed electric field at two different intensities. We found that both stimuli, especially the one with the highest angular frequency and amplitude, modified the electrical charge distribution in the RBD surface and the number of hydrogen bonds. Moreover, the secondary structure was significantly affected, with a decrease of the structured regions, particularly the regions with residues involved in recognizing and interacting with the receptor ACE2. Since many regions suffered conformational changes, we calculated RMSF and ΔRMSF to identify the regions and residues with larger fluctuations and higher flexibility. We found that regions conformed by 353-372, 453-464, and 470-490 amino acid residues fluctuate the most, where the first is considered a therapeutic target, and the last has alreadybeen characterized for its flexibility. Our results indicate that a pulsed electric field can cause loss of stability in the Spike-RBD, and we were able to identify the vulnerable sites to be used as a starting point for the development of viral inhibition or inactivation mechanisms