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

Abstract

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.

• Authors: Manjunath D Meti, Jialiang Lin, Yuhan Wang, Zhibing Wu, Hong Xu, Xu Xu, Qingguo Han, Ming Ying, Zhangli Hu, Zhendan He
• Journal: Journal of biomolecular structure & dynamics (J Biomol Struct Dyn) Vol. 37 Issue 13 Pg. 3379-3387 (08 2019) ISSN: 1538-0254 [Electronic] England
• PMID: 30213239 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Glycosides
• Trypsin Inhibitors
• ligupurpuroside B
• Trypsin

Topics

• Binding Sites
• Circular Dichroism (methods)
• Fluorescence
• Glycosides (pharmacology)
• Humans
• Molecular Docking Simulation
• Protein Binding
• Protein Conformation
• Spectrophotometry, Ultraviolet (methods)
• Trypsin (chemistry, metabolism)
• Trypsin Inhibitors (pharmacology)