Journal of Fluorescence

, Volume 24, Issue 6, pp 1803–1810 | Cite as

Interaction of Cu2+, Pb2+, Zn2+ with Trypsin: What is the Key Factor of their Toxicity?

  • Tong Zhang
  • Hao Zhang
  • Guiliang Liu
  • Canzhu Gao
  • Rutao Liu


Heavy metals possess great endangerment to environment even human health because of their indissolubility and bioaccumulation. The toxicity of heavy metal ions (Cu2+, Pb2+, Zn2+) to trypsin was investigated by fluorescence, synchronous fluorescence, UV–vis absorption, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), and enzyme activity assay. The experimental results showed that toxic effect of heavy metal ions was due to their own characteristic, rather than the electric charges of the ion. Zn2+ could not show the obvious toxicity to trypsin, while the structure and function of trypsin was damaged when the enzyme explored to Cu2+ and Pb2+. From the spectra results, we found that Cu2+ would bind with trypsin, which lead to the fluorescence quenched and hydrophobicity increased. Pb2+ could also change the structure and reduce the activity of trypsin in high concentration. In vitro measurement, the toxicity order of heavy metal ions to trypsin is: Cu2+ > Pb2+ > Zn2+. In addition, isothermal titration calorimetry analysis proved that the interactions between Cu2+, Pb2+, Zn2+ and trypsin were all spontaneous and exothermic, which indicated the adverse effect of these heavy metal ions to trypsin.


Heavy metal ions Trypsin Spectroscopy Isothermal titration calorimetry 



This work is supported by NSFC (20875055, 21277081, 201477067), the Cultivation Fund of the Key Scientific and Technical Innovation Project, Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (708058, 20130131110016) are also acknowledged.

Supplementary material

10895_2014_1469_MOESM1_ESM.doc (2 mb)
ESM 1 (DOC 2065 kb)


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.School of Environmental Science and Engineering, China -America CRC for Environment & Health, Shandong ProvinceShandong UniversityJinanPeople’s Republic of China
  2. 2.Shandong Institute for Food and Drug ControlJinanChina

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