Studies On The Interaction Of2-aminobenzothiazole With Hs-DNA,HSA And Trypsin

Many types of nitrogenous heterocyclic compounds, widely distributed in nature, have important implications for biological activity. Heterocyclic compounds have shown a wide range of trends. Especially nitrogen-containing heterocyclic compounds and their derivatives are used as intermediates in the pharmaceutical, pesticide, dyes and other fine chemical products. Moreover, benzo nitrogen-containing heterocyclic compounds are increasingly favored by researchers in the field of agriculture, medicine, light-emitting materials, organometallic chemistry because of its high selectivity and biological activity.DNA and protein are major component of living organisms. Various toxic and harmful substances come into human bodies often interact with these biological macromolecules to show their harmfulness. Therefore, it is of great importance to investigate the details about the mechanism of toxic action of pollutants to organisms at the level of molecular, which will also help more to assess the toxicity of harmful substances in depth. Also, this will provide some reference and technical support for the relevant standard of protecting human health and safety.In this paper, we studied the toxicity mechanism of2-aminobenzothiazole targeted to herring sperm DNA (hs-DNA), human serum bovine (HSA), trypsin at molecule level by spectroscopy methods and molecular modeling. The dissertation consists of the following three parts.In the first part, the toxic interaction between2-ABT and hs-DNA was investigated using multi-spectroscopic techniques and molecular modeling study. The fluorescence spectroscopy and UV absorption spectroscopy indicated that2-ABT interacted with hs-DNA in groove binding mode. The binding constant and the number of binding sites were7.2×103L mol-1and0.95, respectively. The conformation change of DNA after binding with2-ABT was also confirmed using the circular dichroism spectroscopy (CD). The molecular modeling results illustrated that2-ABT tended to bind in the region of rich A-T base pairs through the hydrogen bond between A18and amino group of2-ABT.In the second part, the interaction between2-ABT and HSA was investigated using multi-spectroscopic techniques and molecular modeling study. The binding constant and binding sites were determined through fluorescence quenching spectra. The site-competitive replacement experiments revealed the precise binding site of2-ABT on HSA. Moreover, molecular docking result illustrated the electrostatic interaction in accordance with the conclusions from the calculated thermodynamic parameters and the effect of ionic strength. UV-vis absorption, three-dimensional (3D) fluorescence, synchronous fluorescence and circular dichroism (CD) spectroscopy showed that the addition of2-ABT changed the conformation of HSA.In the third part, the binding mechanism between2-ABT and trypsin was investigated using multi-spectroscopic techniques and molecular modeling study. The thermodynamic parameters were calculated by fluorescence quenching to determine that the main binding force between2-ABT and trypsin was hydrogen bonds and van der Waals forces. The addition of2-ABT changed the conformation of trypsin. The results of molecular modeling and enzyme activity inferred that it was a non-competitive inhibition, hindering the substrate to the protease active center combination, indirectly lead to a decline in the activity, which damage the body’s normal digestive function.The results of our study indicate that after2-ABT came into the body, it can not only interact with DNA, showing its genotoxicity, but also lead to conformational change of the protein.