Study of the effects of ultrafine carbon black on the structure and function of trypsin

Due to the rapid development of industrial society, air pollution is becoming a serious problem which has being a huge threat to human health. Ultrafine particles (UFPs), one of the major air pollutants, are often the culprits of human diseases. At present, most of the toxicological studies of UFPs focus on their biological effects on lung cells and tissues, but there are less researches taking aim at the negative effects on functional proteins within the body. Therefore, we experimentally explored the effects of ultrafine carbon black (UFCB) on the structure and function of trypsin. After a short‐term exposure to UFCB, the trypsin aromatic amino acid microenvironment, protein backbone and secondary structure were changed significantly, and the enzyme activity showed a trend that rose at first, then dropped. In addition, UFCB interacts with trypsin in the form of a complex. These studies demonstrated the negative effects of UFCB on trypsin, evidencing potential effects on animals and humans. With the increase of ultrafine carbon black (UFCB) concentration, the position of strong absorption peak shifted from 195nm to 194nm, which indicated that the structure of trypsin peptide bond was changed and the protein backbone was contracted. The change of absorption peak near 280nm indicates that the quenching of trypsin fluorescence by UFCB was local static quenching, and the hydrophobicity of aromatic amino acid microenvironment was enhanced.