A new method to determine a ternary phase diagram of benzene–acetic acid–water system is provided to upper-division undergraduate students. The partially miscible liquid phase region can be accurately constructed using isothermal titration microcalorimetry (ITC). Compared with the traditional visual method, ITC can provide precise data and more information about the dissolution process despite the expensive instrument and the long titration time. This experiment can be conditionally incorporated into a physical chemistry laboratory curriculum as a modern acquisition of a classic ternary phase diagram.
For the mixed aqueous solution of LSL and COP, the interaction mode and mechanism have been comprehensively studied using multispectral methods including fluorescence spectrum, ultraviolet-visible (UV-vis )adsorption spectra, and circular dichroism (CD) spectra. The surface activity, particle size, foaming, emulsifying,
The interaction of one anticancer drug (caffeic acid phenethyl ester; CAPE) with three proteases (trypsin, pepsin and α-chymotrypsin) has been investigated with multispectral methods and molecular docking. As an active components in propolis, the findings are of great benefit to metabolism, design, and structural modification of drugs. The results show that CAPE has an obvious ability to quench the trypsin, pepsin, or α-chymotrypsin fluorescence mainly through a static quenching procedure.Trypsin has the largest binding affinity to CAPE, and α-chymotrypsin has the smallest binding affinity to CAPE. The data obtained from thermodynamic parameters and molecular docking prove that the spontaneously interaction between CAPE and each protease is mainly due to a combination of van der Waals (vdW) force and hydrogen bond (H-bond), controlled by an enthalpy-driven process. The binding force, strength, position, and the number of H-bond are further obtained from the results of molecular docking. Through ultraviolet spectroscopy, dynamic light scattering and circular dichroism experiments, the change in the protease secondary structure induced by CAPE was observed. Additionally, the addition of protease had a positive effect on the antioxidative activity of CAPE, and α-chymotrypsin has the greatest effect on the removal of 2,2-diphenyl-1-picrylhydrazyl free radicals by CAPE.α-chymotrypsin, caffeic acid phenethyl ester (CAPE), pepsin, trypsin | INTRODUCTIONCaffeic acid phenethyl ester (CAPE) has been widely used in various regions as a traditional natural medicine. [1] As the main active ingredient of propolis, CAPE has various biological activities, including anticancer, anti-inflammatory, antibacterial, neuroprotective, etc. [2][3][4] In addition, it has a very strong antioxidant capacity, [5] as a polyphenol containing hydroxyl groups in benzenediol. [6] In previous works, the study of the interaction between CAPE and macromolecules mainly focus on the binding mechanism, influencing factors, drug activities, and pharmacology; many theoretical researches have been done.Studies have shown that poly(3-hydroxybutyrate) (PHB) fibre can enhance the antioxidant and antibacterial activities of CAPE. [7] CAPE can inhibit iNOS gene transcription by inhibiting the nuclear factor NF-κB site, and can inhibit the catalytic activity of iNOS, [8] which provides a research basis for the anti-inflammatory and antitumour effects of CAPE. According to reports, after CAPE is compounded with γ-cyclodextrin (γ-CD), the anticancer activity of CAPE will increase. [9] In addition, in the work of this research group, the binding constant of CAPE and bovine serum albumin was $10 6 , of which the main forces are H-bond and vdW force, and the driving mode is enthalpy drive. However, there are few studies on the interaction
Isothermal titration microcalorimetry (ITC) is a common and powerful tool in thermodynamics and related fields, and the connection between the solution behavior and raw titration curve is complex, important, and worth studying, so we try to discuss this problem using a complex solid–solid–liquid diagram. Although there are many experimental methods for studying ternary phase diagrams, ITC has been proven to be a simple, universal method at normal temperature and pressure. This method can be extended to investigate phase diagrams of multisalt aqueous solutions and related systems. Here, the phase equilibrium of one common ternary system ( NaCl + Na 2 SO 4 + H 2 O) was determined using the ITC method with the aid of X-ray diffraction measurements. This isothermal and isobaric titration method can be used not only to determine the boundaries of different phase regions by analyzing changes in the slope of the observed heat vs solvent concentration plot but also to provide additional accurate data regarding the solid dissolution enthalpy and the dilution enthalpy. The dissolution enthalpy of 1 mol NaCl (Na 2 SO 4 ) solid dissolving in water to just form a saturated solution is measured at 1.92 kJ/mol (−15.60 kJ/mol), and the dissolution enthalpy of the mixed solids can be evaluated with these data. The dilution enthalpy is strongly dependent on the solute concentration (0.08–0.23 kJ/mol at the range of concentration studied), and for the same range concentration of a solute, the dilution enthalpy of Na 2 SO 4 is positive and larger than that of NaCl. Therefore, the connection between the observed heat and the microscopic behavior and the separation between the dissolution and dilution data may result in the possibility to gain a clearer understanding about the solution behaviors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.