Study on interaction between curcumin and pepsin by spectroscopic and docking methods.
The interaction between curcumin and pepsin was investigated by fluorescence, synchronous fluorescence, UV-vis absorption, circular dichroism (CD), and molecular docking. Under physiological pH value in stomach, the fluorescence of pepsin can be quenched effectively by curcumin via a combined quenching process. Binding constant (Ka) and binding site number (n) of curcumin to pepsin were obtained. According to the theory of Förster's non-radiation energy transfer, the distance r between pepsin and curcumin was found to be 2.45 nm within the curcumin-pepsin complex, which implies that the energy transfer occurs between curcumin and pepsin, leading to the quenching of pepsin fluorescence. Fluorescence experiments also suggest that curcumin is located more closely to tryptophan residues than tyrosine residues. CD spectra together with UV-vis absorbance studies show that binding of curcumin to pepsin results in the extension of peptide strands of pepsin with loss of some β-sheet structures. Thermodynamic parameters calculated from the binding constants at different temperatures reveal that hydrophobic force plays a major role in stabilizing the curcumin-pepsin complex. In addition, docking results support the above experimental findings and suggest the possible hydrogen bonds of curcumin with Thr-77, Thr-218, and Glu-287 of pepsin, which help further stabilize the curcumin-pepsin complex.
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Ming
M
Ying
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Fengwen
F
Huang
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Haidong
H
Ye
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China. Electronic address: xuhong@szu.edu.cn.
Hong
H
Xu
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Liangliang
L
Shen
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Tianwen
T
Huan
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Shitong
S
Huang
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Jiangfeng
J
Xie
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China.
Shengli
S
Tian
College of Life Sciences, Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shen Zhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, China. Electronic address: huzl@szu.edu.cn.
Zhangli
Z
Hu
School of Medicine, Shenzhen University, Shenzhen, 518060, China.
Zhendan
Z
He
Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand.
Jun
J
Lu
Shenzhen Marine Environment and Resource Monitoring Center, Shenzhen 518060, China.
Kai
K
Zhou
D001665:Binding Sites; D003474:Curcumin / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D062105:Molecular Docking Simulation; D010434:Pepsin A / Q000737:chemistry*; D011485:Protein Binding; D013816:Thermodynamics; D014364:Tryptophan / Q000737:chemistry*
D014364:Tryptophan; D010434:Pepsin A; D003474:Curcumin
Curcumin; Interaction; Pepsin