Synthesis reaction Free Energy

In considering the energetics of a microbially catalyzed reaction, it is important to recall that progress of the redox reaction (e.g., Reaction 18.7) is coupled to synthesis of ATP within the cell, so the overall reaction is the redox reaction combined with ATP synthesis. The free energy liberated by the overall reaction is the energy liberated by the redox reaction, less that consumed to make ATP. The overall reaction s equilibrium point is where this difference vanishes at this point,... 

In plastein synthesis the free energy of formation of the peptide bonds is small, as attested to by the reversal of hydrolysis merely by concentrating certain enzymatic hydrolytic products the synthetic product is insoluble, which tends to drive the reaction toivards synthesis. In these two respects plastein formation resembles reactions of the type benzoyl-L-leucine - - L-leucine anilide to benzoyl-L-leucyUeucine anilide. 

As we have seen, the metabolic energy from oxidation of food materials—sugars, fats, and amino acids—is funneled into formation of reduced coenzymes (NADH) and reduced flavoproteins ([FADHg]). The electron transport chain reoxidizes the coenzymes, and channels the free energy obtained from these reactions into the synthesis of ATP. This reoxidation process involves the removal of both protons and electrons from the coenzymes. Electrons move from NADH and [FADHg] to molecular oxygen, Og, which is the terminal acceptor of electrons in the chain. The reoxidation of NADH,... 

The net free energy change, AG°, for this conversion is —37.7 kj/mol. The consumption of a total of six nucleoside triphosphates drives this process forward. If glycolysis were merely reversed to achieve the net synthesis of glucose from pyruvate, the net reaction would be... 

We next consider the synthesis and chemical reactions of the oxides of chlorine. Because the compounds are strongly endothermic and have large positive free energies of formation it is not possible to prepare them by direct reaction of CI2 and O2. Dichlorine monoxide, CI2O, is best obtained by treating freshly prepared yellow HgO and CI2 gas (diluted with dry air or by dissolution in CCI4) ... 

The production of ammonia is of historical interest because it represents the first important application of thermodynamics to an industrial process. Considering the synthesis reaction of ammonia from its elements, the calculated reaction heat (AH) and free energy change (AG) at room temperature are approximately -46 and -16.5 KJ/mol, respectively. Although the calculated equilibrium constant = 3.6 X 108 at room temperature is substantially high, no reaction occurs under these conditions, and the rate is practically zero. The ammonia synthesis reaction could be represented as follows ... 

Based on a series of studies of the effect of organic solvent on the reaction of Ca-ATPase with Pj and ATP synthesis, De Meis et al. proposed that a different solvent structure in the phosphate microenvironment in Ej and E2 forms the basis for existence of high- and low-energy forms of the aspartyl phosphate [93]. Acyl phosphates have relatively low free energy of hydrolysis when the activity of water is reduced, due to the change of solvation energy. The covalently bound phosphate may also reside in a hydrophobic environment in E2P of Na,K-ATPase since increased partition of Pj into the site is observed in presence of organic solvent [6] in the same manner as in Ca-ATPase. 

Supercritical water (SCW) presents a unique combination of aqueous and non-aqueous character, thus being able to replace an organic solvent in certain kinds of chemical synthesis. In order to allow for a better understanding of the particular properties of SCW and of its influence on the rate of chemical reactions, molecular dynamics computer simulations were used to determine the free energy of the SN2 substitution reaction of Cl- and CH3C1 in SCW as a function of the reaction coordinate [216]. The free energy surface of this reaction was compared with that for the gas-phase and ambient water (AW) [248], In the gas phase, an ion-dipole complex and a symmetric transition... 

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