Conformation change of trypsin induced by acteoside as studied using multiple spectroscopic and molecular docking methods

Abstract

The interaction of trypsin with acteoside was studied using ultraviolet visible absorption, fluorescence, synchronous fluorescence, circular dichroism techniques, along with molecular docking method. The fluorescence experiments indicated that acteoside quenched the intrinsic fluorescence of trypsin via a combined quenching process (static and dynamic quenching). The binding constant of acteoside to trypsin obtained was 2.50 × 10 5 L mol −1 at 298 K and the number of binding site was about one under the same experimental condition. The thermodynamic functions ΔH°and ΔS°of the binding process were 8.79 kJ mol −1 and 132.58 J mol −1 K −1 , respectively, which indicated that the hydrophobic force was the main acting force between them. Ultraviolet-visible, synchronous fluorescence together with circular dichroism spectra studies demonstrated that the interaction of acteoside with trypsin lead to a loosening and unfolding of the protein backbone with partial β-sheet structures being transformed into α-helix structures. All these experimental results were validated and explained reasonably by docking studies. And the molecular docking results further illustrated that besides hydrophobic forces, hydrogen bonds also played an important role in the stabilization of the acteoside-trypsin complex. Results from this study should be helpful to make full use of acteoside in the food industry and be useful to the design of the drugs for the diseases related to trypsin.

The impact of nano-polystyrene on human serum albumin–paracetamol interactions: understanding the impact on therapeutic development and safety

“…39 The red shift indicates conformational changes leading to an increase in the hydrophilicity of the protein. 40 The increase in hydrophilicity increased the binding of paracetamol to the protein, which might hinder the release of the drug. From the graphs, it is evident that paracetamol–HSA had a stronger interaction with the tryptophan residue in the binding site.…”

Discrimination of mycoplasma infection using machine learning models trained on autofluorescence signatures of host cells

“…After counting the cell number in the cell suspension, cells were seeded into μ-Slide VI 0.4 (Ibidi, Gräfelfing, Germany) with thin polymer coverslips at the culture bottom. Note that trypsin is known as a fluorescent protein 26 and may interfere with cellular autofluorescence signals. However, each seeded culture could be contaminated with almost the equal amount of trypsin even after the washing step, we speculated that the effect of trypsin on autofluorescence signals in mycoplasma (−) and mycoplasma (+) cells was negligible.…”

Application of Molecular Simulation Methods in Food Science: Status and Prospects

“…Four phenylpropanoid glycosides have also been proven to possess inhibitory activity against trypsin; among these, acteoside had the highest, followed by syringalide A 3′-α- l -rhamnopyranoside, lipedoside A-I, and osmanthuside B. A molecular docking study showed that the phenolic hydroxyl group on the A ring had a greater effect on the inhibitory activity than it did that on the B ring, because the A ring was closer to the binding pocket and was able to form more hydrogen bonds with the key residues Ser-217, Ser-190, Gly-219, and Ser-195 …”