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Concepts of Potential Energy, Enthalpy, and Bond Energy Calculations
Published in Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk, Survival Guide to General Chemistry, 2019
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk
A reversible reaction is one in which both the forward reaction and the reverse reaction can occur at the same time. Reversible reactions can be read on a single potential energy diagram. In these cases the forward reaction is read from left-to-right and the reverse reaction is read from right-to-left.
Simple Receptor-Ligand Interactions
Published in John C. Matthews, 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.
Aspartic Acid Racemization and Aging in Cartilaginous Tissue
Published in Sara C. Zapico, Mechanisms Linking Aging, Diseases and Biological Age Estimation, 2017
Sarit Sara Sivan, Alice Maroudas, Ellen Wachtel
Accumulation of D-Asp depends upon competition between two linear processes described by the rate constants of racemization (ki) and of protein turnover (kT). When the amount of D-isomer is small (D/L < 0.15), racemization may be considered irreversible. This is generally the case in the tissues discussed here; a reverse reaction would be subsumed in protein turnover. The time rate of change of the amount of D-isomer can be written as (Maroudas et al. 1998):
Photoperiod-dependent changes in oxidative stress markers in the blood of Shetland pony mares and stallions involved in recreational horseback riding
Published in Chronobiology International, 2022
Natalia Kurhaluk, Oleksandr Lukash, Halyna Tkachenko
LDH catalyzes the redox reaction, that is, the reversible conversion between pyruvate and L-lactate. L-lactate formation consumes reduced nicotinamide adenine dinucleotide (NADH2) and generates oxidized nicotinamide adenine dinucleotide (NAD+), whereas NADH2 is produced during the oxidation of L-lactate to pyruvate and the final product of glycolysis to lactate when oxygen is absent or in short supply. It also performs the reverse reaction through the Cori cycle in the liver (Adeva et al. 2013). In this respect, the increased LDH activity in the mares in spring was the result of an anaerobic energy supply. Defense against the lack of oxygen in hypoxia-tolerant animals, accordingly, implicates (a) a reduction in energy turnover and/or (b) improvement of energetic efficiency in other metabolic processes (Hochachka 1997). The LDH activity in the plasma of the mares and stallions before exercise (at rest) was shown in the autumn period, and the maximum values were recorded during the summer and winter photoperiods. The exercise determined the activity of this enzyme in the plasma of the stallions, with minimum and maximum values in the autumn and winter photoperiods, respectively. The values of glucose and bilirubin in the plasma of the Shetland ponies did not changed statistically significantly throughout the study period.
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.
Sirtuins: potential therapeutic targets for regulating acute inflammatory response?
Published in Expert Opinion on Therapeutic Targets, 2020
Vidula Vachharajani, Charles E. McCall
While nicotinamide is removed during deacetylation reaction, evidence suggests that nicotinamide can promote the reverse reaction where the substrates are formed and sirtuin is inhibited, thus acting as a sirtuin inhibitor [12]. Isonicotinamide, with competitive inhibition of nicotinamide, acts as a sirtuin activator [13]. sirtuin inhibitors mainly consist of molecules that bind to the NAD+ binding site partially or completely [9]. Resveratrol is a known sirtuin activator. While controversy regarding direct sirtuin1 activation by resveratrol, evidence suggests that resveratrol increases NAD+ levels via activation of AMP kinase with a concomitant increase in sirtuin1 deacetylase activity [14].