Reaction, endergonic

Reactions are classified as exergonic or endergonic according to the sign of AG°. An exergonic reaction is one in which AG° is negative, an endergonic reaction has a positive value of AG°. 

If free energy is stored and transfened by way of ATP, where does the ATP come from It comes from ADP by the endergonic reaction... 

Markovnikov s rule can be restated by saying that, in the addition of HX to an aikene, the more stable carbocation intermediate is formed. This result is explained by the Hammond postulate, which says that the transition state of an exergonic reaction step structurally resembles the reactant, whereas the transition state of an endergonic reaction step structurally resembles the product. Since an aikene protonation step is endergonic, the stability of the more highly substituted carbocation is reflected in the stability of the transition state leading to its formation. 

Hammond postulate (Section 6.10) A postulate stating that we can get a picture of what a given transition state looks like by looking at the structure of the nearest stable species. Exergonic reactions have transition states that resemble reactant endergonic reactions have transition states that resemble product. 

Enantiotopic (NMR), 455 Endergonic. 153 Endergonic reaction, Hammond postulate and, 197-198 Endo stereochemistry, Diels-Alder reaction and, 495 Endothermic, 154 -ene, alkene name ending, 176 Energy difference, equilibrium position and, 122... 

ATP is involved in many endergonic reactions necessary for cell metabolism, for example, the first stage of glucose utilization catalyzed by hexokinase ... 

Figure 10-3. Transfer of free energy from an exer-gonic to an endergonic reaction via a high-energy intermediate compound ( (E)).

Significance of the Br nsted Slope in Electron Transfer. Linear free energy relationships have been extensively studied for electron transfer and related reactions in both inorganic and organic systems. For highly endergonic reactions, the Br0nsted slope a is close to unity. In many cases, however, the more or... 

In conclusion, the free energy change of an ET step is already a good indicator of the feasibility of the reaction. A highly endergonic reaction, with, say, AG° > 20 kcal mol-1, corresponds to a rather slow ET reaction that is not likely to compete with other reactions of polar nature. In the region where AG° lies between 20 and -A kcal mol-1, we need to apply the Marcus approach in order to get an approximate value of the ET rate constant, whereas at AG° < - A kcal mol-1 most intermolecular ET reactions appear to be diffusion controlled. 

Introductions to enzyme kinetics and bioenergetics are given with explanations of key terms such as Km and Vmax coenzymes, cofactors and inhibitors typical metabolic reactions free energy exergonic and endergonic reactions, catabolism and anabolism. 

Why does metabolism not grind to a resounding halt when an endergonic reaction occurs within a pathway ... 

Figure 2.2 Reaction progress graph endergonic reaction...

Not all endergonic reactions will be so conveniently placed adjacent to an exergonic reaction. In such a situation, the required energy is usually supplied by ATP ... 

The hydrolysis of adenosine triphosphate (ATP), an exergonic reaction [Equation (7.89)], is frequently used in biologic systems to drive endergonic reactions. The value of AGmfor this reaction is —29,3001 mol ... 

For ATP to carry out this function, it has to be produced from adenosine diphosphate (ADP) in an endergonic reaction that must be driven by another exergonic metabolic reaction. One exergonic reaction step that occurs in the overall oxidation of glucose in the cell is the oxidation of 3-phosphoglyceraldehyde to 3-phosphoglycerate by pyruvate, for which AG = —29,300 Jmol ... 

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