Simple Receptor-Ligand Interactions
John C. Matthews in Fundamentals of Receptor, Enzyme, and Transport Kinetics, 2017
Establishment of chemical equilibrium does not mean that the reaction has stopped. Every instant, molecules of R and L are combining to form RL and molecules of RL are dissociating to form R and L. At equilibrium these reactions have reached a balance such that for each RL that dissociates an R and an L combine to replace it. The change that has occurred in the system to allow it to reach equilibrium is in the relative concentrations of reactants and products. We can see from Figure 3 that as the reaction proceeds the concentrations of the reactants decrease and the steepness of the slope of the curve decreases. The rate constant (as the term would suggest) remains constant. Thus, the reaction rate decreases in direct proportion to the concentrations of the reactants. Similarly, the rate of the reverse reaction increases with time as the concentration of the reactant for the reaction in the reverse direction increases. Eventually the reaction reaches a state where the forward and reverse reaction rates are equal. This is equilibrium.
The Inducible System: Antigens
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
the concentrations of reactants (A + B) and products (C + D) change until a constant concentration of each is attained. At this point, the rate of product formation (the forward reaction) equals the rate of reactant formation (the reverse reaction). The result is called chemical equilibrium. There is no net change in the concentrations of the reactants at equilibrium unless product is removed. This equilibrium is, therefore, dynamic. If some product is removed, the forward reaction replaces it, reestablishing the equilibrium. The equilibrium point is a constant for any reaction.
Introduction: Background Material
Nassir H. Sabah in Neuromuscular Fundamentals, 2020
A reversible reaction proceeds in both the forward direction (reactants ⟶ products) and the reverse direction (products ⟶ reactants), resulting after a sufficiently long time in a state of dynamic equilibrium consisting of a mixture of reactants and products. For example, consider the simple, first-order reaction:
LncRNA NEAT1 promotes airway smooth muscle cell inflammation by activating the JAK3/STAT5 pathway through targeting of miR-139
Published in Experimental Lung Research, 2021
Meng-Xia Zhu, Lin-Hui Huang, Yi-Ke Zhu, Xing-Jun Cai
ASMCs were treated with control, sh-NC, sh-NEAT1, OE-NC or OE-NEAT1, and total RNA was extracted using Trizol reagent (ThermoFisher Scientific, USA). Briefly, reverse transcription was performed with an Oligo_(dT)18 and SuperScript IV first strand synthesis system (ThermoFisher Scientific, USA). The reverse reaction conditions were as follows: 25 °C, 10 min; 50 °C, 45 min; 85 °C, 5 min. Q-PCR was performed by SYBR master mix (TAKARA, Japan) and ABI Prism SDS 7000 (ABI, USA) with the following procedures: 95 °C, 5 min, 95 °C, 30 seconds, 55 °C, 30 seconds, 72 °C, 10 seconds, 4 °C, 1 h, 35 total cycles. The housekeeping gene GAPDH was set as the internal control, and the relative gene expression was calculated by 2-△△CT. The primer forward (PF) and primer reverse (PR) are described in Table 1.
Effect of first order chemical reactions through tissue-blood interface on the partial pressure distribution of inhaled gas
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
We assumed chemically reactive fluid (blood) is flowing through a thin cylindrical capillary tube of radius Rt which is surrounded by a tissue of radius Rc as shown in Figure 2 (Ng and Rudraiah 2008; Hall and Guyton 2010; Saini et al. 2014). The material of tissue is porous, absorptive, and reactive. Also, we considered the flow of solute (gas) is going through the tissue-blood capillary interface and at the tube wall there are two linear chemical reactions are taking place, first is irreversible and another is reversible. Under irreversible reaction, some portion of the gas is consumed by the wall material while in reversible reaction some portion of the gas is used in a phase exchange process with the flowing blood. During the phase exchange process the gas which is flowing with the fluid is called mobile phase and which is stick with or absorbed by the boundary is named as an immobile phase. The fluid is Newtonian and the circulation of blood flow inside the body section is homogeneous, unsteady, laminar, fully-developed while there is radial symmetry on the axis of a small diameter long regular straight tube.
Xenobiotic C-sulfonate derivatives; metabolites or metabonates?
Published in Xenobiotica, 2018
Following its administration to man the major metabolites resulted from a reduction of the side-chain double bond and carbonyl groups or cleavage at the side chain and excretion of these products in the urine as their glucuronic acid conjugates (Lautala et al., 1997; Pentikäinen et al., 1990; Taskinen et al., 1991). A similar array of metabolites was found in other animals but the overall metabolism of this nitrocatechol was more complicated and there has been mention of a “bisulfite adduct of nitecapone” in the urine of rats and dogs (Figure 3). This particular metabolite was resistant to attempts at hydrolysis with arylsulfatase/β-glucuronidase (H. pomatia) (Wikberg & Taskinen, 1993; Wikberg & Vuorela, 1994). It had been noticed previously that the α,β-double bond in the side chain of the nitecapone molecule was able to react at physiological pH with the free thiol group in cysteine and glutathione to yield “sulfydryl-adducts”. This process occurred at physiological pH but was a pH-dependent reversible reaction and under acidic conditions the equilibrium was in favor of the free reactants. However, no evidence for glutathione pathway metabolites has been found in the urine of rats and dogs (Wikberg & Taskinen, 1993). Nevertheless, adduct formation with thiol groups was thought to partially underlie the compound’s gastroprotective effect (Korkolainen et al., 1990).
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