Evaluation of the binding mechanism of iodine with trypsin and pepsin: A spectroscopic and molecular docking

Yanqing Wang; Qianqian Han; Gencheng Zhang; Hongmei Zhang

doi:10.1016/j.saa.2020.118036

Evaluation of the binding mechanism of iodine with trypsin and pepsin: A spectroscopic and molecular docking

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Apr 5:230:118036. doi: 10.1016/j.saa.2020.118036. Epub 2020 Jan 7.

Authors

Yanqing Wang¹, Qianqian Han², Gencheng Zhang³, Hongmei Zhang⁴

Affiliations

¹ Institute of Environmental Toxicology and Environmental Ecology, Yancheng Teachers University, Yancheng City, Jiangsu Province 224051, People's Republic of China; School of Chemical and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China. Electronic address: wyqing76@126.com.
² School of Chemical and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China; Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing City, Jiangsu Province 210009, People's Republic of China.
³ School of Chemical and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China.
⁴ Institute of Environmental Toxicology and Environmental Ecology, Yancheng Teachers University, Yancheng City, Jiangsu Province 224051, People's Republic of China; School of Chemical and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China. Electronic address: hxzhm@126.com.

PMID: 31931358
DOI: 10.1016/j.saa.2020.118036

Abstract

In this work, the effects of I₂ on the activities and conformational structures of digestive enzymes, trypsin and pepsin were studied. The results indicated that the enzyme activities were decreased to some extent in the presence of I₂, especially trypsin. Upon gradual addition of I₂, the intrinsic fluorescence quenching of trypsin and pepsin were observed by mainly static collision and hydrophobic forces. I₂ is more likely to cause the fluorescence quenching of trypsin than that of pepsin. Compared with pepsin, trypsin has a greater ability to bind with I₂. The synchronous fluorescence spectral results indicated that I₂ induced the quaternary structure changes of trypsin/pepsin and changed the hydrophobicity of Tyr and Trp residues. In addition, molecular docking was used to obtain the binding mode and the various amino acid residues of trypsin and pepsin with I₂. These investigations may constitute a solid work to further explain the process of migration and transformation of I₂ in digestive system.

Keywords: Activity; Inhibition mechanism; Iodine; Pepsin; Trypsin.

MeSH terms

Animals
Iodine / pharmacology*
Molecular Docking Simulation
Pepsin A / antagonists & inhibitors
Pepsin A / chemistry
Pepsin A / metabolism*
Protease Inhibitors / pharmacology*
Protein Binding
Protein Structure, Quaternary / drug effects
Swine
Trypsin / chemistry
Trypsin / metabolism*
Trypsin Inhibitors / pharmacology*

Substances

Protease Inhibitors
Trypsin Inhibitors
Iodine
Trypsin
Pepsin A