Disease Prediction and Drug Development
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam in Introduction to Computational Health Informatics, 2019
Michaelis–Menten equations (see Equations 10.5 and 10.6) are used to study the kinetics of enzyme's reaction. The rate of reaction is measured at different substrate concentration values. The Michaelis constant Km is the substrate concentration at which the reaction-rate is 50% of the maximum reaction-rate at the saturation point. The flux J through the linear pathway of n unimolecular reversible reaction is given by Michaelis–Menten equations. The substrates in the chain-reactions are denoted as Si (1 ≤ i ≤ n + 1) with S1 as the initial substrate and Sn+1 as the final substrate. The equilibrium constants K1→j is the product of reaction constants from reaction one to reaction Sj −1 → Sj. The coefficient is the Michaelis constant for the jth reaction.
Thermodynamics Entropy and Free Energy
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk in Survival Guide to General Chemistry, 2019
Any mixture of exactly 1 Molar reactants and products for a reversible reaction will proceed in the spontaneous direction given by the standard enthalpy and entropy, expressed as a value for ΔG°T. The reaction will continue until the concentration of products in the spontaneous direction build up to the point where the concentration entropy exactly cancels the ΔG°T: this is the point of equilibrium. The equilibrium constant defines the corresponding concentrations.
ENZYME-CATALYZED REACTIONS
David M. Gibson, Robert A. Harris in Metabolic Regulation in Mammals, 2001
The value for AG' under these conditions is defined as the constant AG°', the standard free energy of this reaction (at pH7.0). It is a function of the equilibrium constant. The standard free energy and equilibrium constants of many reactions are now known. With either of these constants the actual free energy for any set of initial conditions can
Preparation of curcumin self-micelle solid dispersion with enhanced bioavailability and cytotoxic activity by mechanochemistry
Published in Drug Delivery, 2018
Qihong Zhang, Nikolay E. Polyakov, Yulia S. Chistyachenko, Mikhail V. Khvostov, Tatjana S. Frolova, Tatjana G. Tolstikova, Alexandr V. Dushkin, Weike Su
Additionally, the equilibrium constant (Ks) of this system was calculated according to Equation (1). All results of calculation using Equation (1) and (2) are displayed in Table 1. The values of stability constant K and ΔG of Na2GA/Cur (1/1 and 2/1) were nearly the same. But increasing content of Na2GA to Cur (4/1) decreased the stability constant K and ΔG, which probably suggested that weaker inclusion of Cur molecules into micelles of GA. Additionally, ΔH values for all samples were negative, and their exact values were not shown due to the large estimated error, as mentioned previously. Therefore, the thermodynamics parameters indicated that the formation of this inclusion complex could spontaneously complete (ΔG < 0), and the inclusion process was exothermic (ΔH < 0).
Application of crosslinked chitosan-nanoclay composite beads for efficient removal of Ponceau S azo dye from aqueous medium
Published in Toxin Reviews, 2023
Seda Çınar, Ayşe Dinçer, Ahmet Eser, Tülin Aydemir
The adsorption dynamics can be evaluated by thermodynamic studies. To understand the adsorptive behavior of Ponceau S on crosslinked CS/NC composite beads, thermodynamic parameters were calculated. The free energy change (ΔG°, kJ/mol), enthalpy change (ΔH°, kJ/mol K) and entropy change (ΔS°, kJ/mol K) for the adsorption of dye was calculated using the following equations (3) and (4): Kc is the adsorption equilibrium constant. Enthalpy (ΔH°) and entropy (ΔS°) were calculated from the slope and intercept from the plot of ln Kc versus 1/T. Where Kc = (CA/Ce) is the adsorption equilibrium constant, CA is the amount of Ponceau S dye adsorbed on the CS/NC composite beads at equilibrium (mg/L); Ce is the equilibrium concentration of the Ponceau S dye in the solution (mg/L). T (K) is the absolute temperature; R is the gas constant (Cheruiyot et al.2019, Banisheykholeslami et al.2021, Priyadarshini et al.2021, Sultana et al.2022). ln KC-1/T graphics and the calculated thermodynamic parameters were given in Figure 5 and Table 3.
Mercury(II) decontamination using a newly synthesized poly(acrylonitrile-acrylic acid)/ammonium molybdophosphate composite exchanger
Published in Toxin Reviews, 2022
Adel A. El-Zahhar, Abubakr M. Idris
The Van’t Hoff plot, lnkd against the reciprocal of absolute temperature (1/T), is shown in Figure 3(d). The results show that the amount of Hg(II) adsorbed on either P(AN-AA)/AMP or P(AN-AA) resins increased as reaction temperature increased. This finding could be attributed to that Hg(II) ions become more mobile at high temperatures and have sufficient energy to interact with the resin active sites. Furthermore, the resins could be highly swelled at high temperatures, which facilitate ions to penetrate within the resin particles resulting in adsorption increase (Doğan and Alkan 2003). The reaction thermodynamics, that is, free energy (ΔG°) (kJ/mol), enthalpy (ΔH°) (kJ/mol), and entropy (ΔS°) (J/mol.K) changes, were determined using Equations (9), (10), and (11); where kd is the equilibrium constant, T (K) is the absolute temperature, R is the gas constant (8.314 J/mol.K), ΔG° is standard free energy changes (J); R is the universal gas constant, 8.314 J/mol K, and T is the absolute temperature (K).
Related Knowledge Centers
- Chemical Equilibrium
- Dissociation Constant
- Ionic Strength
- Hemoglobin
- Reaction Quotient
- Acid–Base Homeostasis
- Stability Constants of Complexes
- Binding Constant
- Reversible Reaction
- Chemical Equation