The hazardous effects of the environmental toxic gases on amyloid beta-peptide aggregation: A theoretical perspective

Alzheimer's disease (AD) is one of the leading causes of dementia in elderly people. It has been well documented that the exposure to environmental toxins such as CO, CO2, SO2 and NO2 that are present in the air is considered as a hallmark for the progression of Alzheimer's disease. However, their actual mechanism by which environmental toxin triggers the aggregation of A beta 42 peptide at the molecular and atomic levels remain unknown. In this study, molecular dynamics simulation was carried out to study the aggregation mechanism of the A beta(42) peptide due to its interaction of toxic gas (CO, CO2, SO2 and NO2). During the 400 ns simulation, all the Af beta(42) interacted toxic gas (CO, CO2, SO2, and NO2) complexes have smaller Root Mean Square Deviation values when compared to the A beta(42) peptide, which shows that the interaction of toxic gases (CO, CO2, SO2, and NO2) would increase the A beta(42) peptide structural stability. The radius of gyration analysis also supports that A beta(42) interacted CO2 and SO2 complexes have the minimum value in the range of 0.95 nm and 1.5 nm. It is accounted that the A beta(42) interacted CO2 and SO2 complexes have a greater compact structure in comparison to A beta(42) interacted CO and NO2 complexes. Furthermore, all the A beta(42) interacted toxic gas (CO, CO2, SO2, and NO2) complexes exhibited an enhanced secondary structural probability for coil and turn regions with a reduced a-helix probability, which indicates that the interaction of toxic gases may enhance the toxicity and aggregation of A beta(42).