Ming Ying,Manjunath D. Meti,Hong Xu,Yuhan Wang,Jialiang Lin,Zhibing Wu,Qingguo Han,Xu Xu,Zhendan He,Wenxu Hong,Zhangli Hu
The interaction of lipase with Ligupurpuroside B was studied by multiple spectroscopic techniques , enzyme activity and molecular modeling under simulative physiological condition. According to Stern-Volmer equation, fluorescence of lipase was quenched by Ligupurpuroside B via a static quenching mechanism because of formation of Ligupurpuroside B-lipase complex. Binding constants , number of binding sites & thermodynamic parameters were evaluated. The values of Δ G o (−25.085 kJ mol −1 ), Δ H o (−12.14 kJ mol −1 ) and Δ S o (+43.45 J mol −1 K −1 ) at 298 K indicated that Ligupurpuroside B-lipase interaction is spontaneous and hydrophobic interaction is the main force stabilizing the Ligupurpuroside B-lipase complex. The enzyme activity assay showed that Ligupurpuroside B inhibited lipase activity efficiently. Synchronous fluorescence spectra (SFS) suggested that Ligupurpuroside B is closer to Trp residues than to Tyr residues. All above experimental results were confirmed by molecular docking studies, which further indicated the binding site of Ligupurpuroside B on the surface of lipase, and the amino acid residues of lipase interacting with Ligupurpuroside B. Our present research work gives valuable information on the design of drugs with lipase as a carrier and should be useful for food industries.
Manjunath D. Meti,Jialiang Lin,Yuhan Wang,Zhibing Wu,Hong Xu,Xu Xu,Qingguo Han,Ming Ying,Zhangli Hu,Zhendan He
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
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