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J Biomol Struct Dyn. 2018 Nov 17:1-9. doi: 10.1080/07391102.2018.1515115. [Epub ahead of print]

Trypsin inhibition by Ligupurpuroside B as studied using spectroscopic, CD, and molecular docking techniques.

Meti MD1,2, Lin J1,2, Wang Y1,2, Wu Z1,2, Xu H1,2, Xu X1,2, Han Q1,2, Ying M1,2, Hu Z1,2, He Z3.

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a Shenzhen Key Laboratory of Marine Bioresources and Ecology/Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography , Shenzhen University , Shenzhen , China.
b Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering , Shenzhen University , Shenzhen , China.
c School of Medicine , Shenzhen University , Shenzhen , China.


It is well known that Ligupurpuroside B is a water-soluble polyphenolic compound and used to brew bitter tea with antioxidant activities. It acted as a stimulant to the central nervous system and a diuretic (increase the excretion of urine), was used to treat painful throat and high blood pressure, and also exerted weight-loss function. In this regard, a detailed investigation on the mechanism of interaction between Ligupurpuroside B and trypsin could be of great interest to know the pharmacokinetic behavior of Ligupurpuroside B and for the design of new analogues with effective pharmacological properties. Ligupurpuroside B successfully quenched the intrinsic fluorescence of trypsin via static quenching mechanism. The binding constants (Ka) at three temperatures (288, 298, and 308 K) were 1.7841 × 104, 1.6251 × 104 and 1.5483 × 104 L mol-1, respectively. Binding constants revealed the stronger binding interaction between Ligupurpuroside B and trypsin. The number of binding sites approximated to one, indicating a single class of binding for Ligupurpuroside B in trypsin. The enzyme activity result suggested that Ligupurpuroside B can inhibit trypsin activity. Thermodynamic results revealed that both hydrogen bonds and hydrophobic interactions play main roles in stabilization of Ligupurpuroside B-trypsin complex. Circular dichroism (CD) results showed that the conformation of trypsin changed after bound to ligupurpuroside B. Molecular docking indicated that Ligupurpuroside B can enter the hydrophobic cavity of trypsin and was located near Trp215 and Tyr228 of trypsin. Communicated by Ramaswamy H. Sarma.


Fluorescence; Ligupurpuroside B; circular dichroism; molecular docking; trypsin

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