The Toxicity Evaluation Of Sodium Benzoate To Organism At The Molecular Level By Spectroscopies

With the development of technology and industry, a large number of pollutants are discharged into the environment around us in an organized or unorganized way, which threats our security and health. However, that is not the only way we get touch in the toxic substance. Something with potential negative effects, like food additives, is focused increasingly.Sodium benzoate is the food preservatives with longest history, and it was always seen as a safe additive in food, which becomes controversial. This research is to investigate the toxicity of sodium benzoate to total four important proteins of organisms by several spectroscopic technologies, including fluorescence spectroscopy (steady-state fluorescence spectroscopy, synchronous fluorescence spectroscopy), UV-visible absorption spectroscopy and circular dichroism spectroscopy under mimic physiological conditions. And the AutoDock software is employed to calculate the model of new-formed structure in needed.The selected proteins in experiments are bovine serum albumin (BSA), bovine hemoglobin (BHb), trypsin and catalase, and the paper is separated into four parts accordingly.Sodium benzoate could unfold BSA and BHb by affecting the peptides of the skeletons and fluctuating the content of main secondary structure as a-helix and P-sheet, which leads to more exposure of internal amino acid groups and the obvious intrinsic fluorescence quenching with the rising concentration of sodium benzoate. The results of spectroscopic measurements indicated that sodium benzoate changed the internal microenvironment of BSA and BHb, resulted in polarity increasing, and induced the alteration of the whole molecule. BSA or BHb and sodium benzoate interacted with each other both by1:1to produce substances by van der Waals forces and hydrogen bond, and the new-formed substances both may partly dissolved with higher temperature.Sodium benzoate could unfold trypsin by decreasing the β-sheet structure, which leads to more exposure of internal amino acid groups and the obvious intrinsic fluorescence quenching with the rising concentration of sodium benzoate. The alteration of the whole molecule may influence the functions, which were performed toxic effects on the organism, even induce some diseases. Trypsin and sodium benzoate interacted with each other to produce a substance by van der Waals forces and hydrogen bond, while the binding site on trypsin is not near to the catalytic triad. So there is not a large influence on the activity of trypsin.Sodium benzoate could unfold catalase by affecting the peptides of the skeletons and fluctuating the content of main secondary structure, which changed the internal microenvironment of catalase. But it is induced not fluorescence quenching but increasing, and the variations are milder compared with that of other three proteins.To sum up, sodium benzoate can influence the structures of all proteins we selected, and easy to penetrate into the biomolecules, change the internal microenvironment and result in polarity increasing around fluorescent groups. All these may affect the functions of each protein.