Mechanism and Nature of Inhibition of Trypsin by Ligupurpuroside A, a Ku-Ding Tea Extract, Studied by Spectroscopic and Docking Methods

IntroductionThe application of nanoparticles (NPs) in medicine and biology has received great interest due to their novel features. However, their adverse effects on the biological system are not well understood.Materials and methodsThis study aims to evaluate the effect of cerium oxide nanoparticles (CNPs) on conformational changes of human hemoglobin (HHb) and lymphocytes by different spectroscopic (intrinsic and synchronous fluorescence spectroscopy and far and near circular dichroism [CD] spectroscopy), docking and cellular (MTT and flow cytometry) investigations.Results and discussionTransmission electron microscopy (TEM) showed that CNP diameter is ~30 nm. The infrared spectrum demonstrated a strong band around 783 cm−1 corresponding to the CNP stretching bond. Fluorescence data revealed that the CNP is able to quench the intrinsic fluorescence of HHb through both dynamic and static quenching mechanisms. The binding constant (Kb), number of binding sites (n), and thermodynamic parameters over three different temperatures indicated that hydrophobic interactions might play a considerable role in the interaction of CNPs with HHb. Synchronous fluorescence spectroscopy indicated that microenvironmental changes around Trp and Tyr residues remain almost unchanged. CD studies displayed that the regular secondary structure of HHb had no significant changes; however, the quaternary structure of protein is subjected to marginal structural changes. Docking studies showed the larger CNP cluster is more oriented toward experimental data, compared with smaller counterparts. Cellular assays revealed that CNP, at high concentrations (>50 µg/mL), initiated an antiproliferative response through apoptosis induction on lymphocytes.ConclusionThe findings may exhibit that, although CNPs did not significantly perturb the native conformation of HHb, they can stimulate some cellular adverse effects at high concentrations that may limit the medicinal and biological application of CNPs. In other words, CNP application in biological systems should be done at low concentrations.

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“…29 The Stern-Volmer equation has been widely used for the determination of quenching mechanism of proteins in the presence of ligands. 30…”

Section: Fluorescence Studiesmentioning

confidence: 99%

Biophysical, docking, and cellular studies on the effects of cerium oxide nanoparticles on blood components: in vitro

Eskandari¹,

Babadaei²,

Nikpur³

et al. 2018

IJN

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“…23 The weak absorption peak at 280 nm is attributed to the aromatic amino acids (tryptophan, tyrosine, and phenylalanine) and is often used to reflect changes in protein conformation. 24 Because peptides cuts after tyrosine, phenylalanine and tryptophan by pepsin, enzyme activity was detected at 280 nm through the peak created by aromatic amino acids. The unit of activity (Unit/ml) for pepsin was defined as the amount of substrate (in micrograms) converted per minute by 1 ml of enzyme under optimal conditions.…”

Section: Pepsinmentioning

confidence: 99%

Eco‐friendly approach on wool pretreatment and effect on the wool structure and dyeability

Türkoğlu

Avcı

Erkan

et al. 2022

Coloration Technology

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This research investigated the effect of various proteolytic enzymatic pretreatment on morphological and chemical features and the dyeability properties of wool fibres. Scoured merino wool fibres are treated with protease, papain, trypsin, and pepsin in specified conditions. Each enzyme activity measurement was provided by appropriate methods such as Bradford, BAPNA (N-benzoyl-1-arginine-p-nitroanilide), and BSA (Bovine Serum Albumin). Enzymatic processes were carried out for 24 h in the incubator set at 40 C, 100 rpm, and specified pH with 1 mg/ml enzyme concentration. Whiteness index (Stensby) and yellowness index (ASTM D 1925) were examined after enzymatic pretreatment. Pepsin and trypsin-treated wool fibres showed the highest whiteness index as 61.3 and 61.1, respectively whilst untreated wool fibres had 52.2. Fourier-transform infrared (FTIR) analysis revealed the increase in the intensity of amide-related bands and hydroxyl bands after enzymatic treatment.Scanning electron microscopy (SEM) photomicrographs manifested the cuticle layer is partially removed in enzyme-treated fibres. Elemental identification was provided by SEM-energy-dispersive X-ray spectroscopy (EDX). It appears that the sulphur bonds decreased after the treatment and the pepsin-treated fibres have fewer bonds of all. To examine the damage to the structure, photomicrographs were taken using fluorescence and light microscopes. The alkali solubility test (ASTM D1283) was also conducted to compare different enzyme types. Wool fibres were dyed in 2.0% concentration with reactive dyestuff. Dyeability and colorimetric features of fibres were measured by a spectrophotometer. The washing fastness test showed that all the samples have good results and the colour change after washing was better in enzyme-treated samples (grade 5) compared to untreated wool fibres (grade 4-5).

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“…Besides traditional spectroscopic methods including ultraviolet visible, [10,11] fluorescence, infrared, and circular dichroism (CD), [12,13] some other techniques such as isothermal titration calorimetry [14] and molecular simulation [15,16] have also been proposed to assess the drug-binding ability of biological macromolecules.…”

Section: Introductionmentioning

confidence: 99%

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

Huang

et al. 2018

International Journal of Food Properties

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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.

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Mechanism and Nature of Inhibition of Trypsin by Ligupurpuroside A, a Ku-Ding Tea Extract, Studied by Spectroscopic and Docking Methods

Cited by 21 publications

References 42 publications

Biophysical, docking, and cellular studies on the effects of cerium oxide nanoparticles on blood components: in vitro

Biophysical, docking, and cellular studies on the effects of cerium oxide nanoparticles on blood components: in vitro

Eco‐friendly approach on wool pretreatment and effect on the wool structure and dyeability

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

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