発エネルギー性の、エネルギー発生性の

WordNet

(biochemistry) of a process accompanied by the release of energy; "diffusion is an exergonic process"

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/28 03:12:01」(JST)

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An exergonic process is one in which there is a positive flow of energy from the system to the surroundings. This is in contrast with an endergonic process.^[1] Constant pressure, constant temperature reactions are exergonic if and only if the Gibbs free energy change is negative (∆G < 0). "Exergonic" (from the prefix exo-, derived for the Greek word ἔξω exō, "outside" and the suffix -ergonic, derived from the Greek word ἔργον ergon, "work") means "releasing energy in the form of work". In thermodynamics, work is defined as the energy moving from the system (the internal region) to the surroundings (the external region) during a given process.

All physical and chemical systems in the universe follow the second law of thermodynamics and proceed in a downhill, i.e., exergonic, direction. Thus, left to itself, any physical or chemical system will proceed, according to the second law of thermodynamics, in a direction that tends to lower the free energy of the system, and thus to expend energy in the form of work. These reactions occur spontaneously.

A chemical reaction is also exergonic when spontaneous. Thus in this type of reactions the Gibbs free energy decreases. The entropy is included in any change of the Gibbs free energy. This differs from a exothermic reaction or a endothermic reaction where the entropy is not included. The Gibbs free energy is calculated with the Gibbs-Helmholtz equation:

where:

T = Temperature in Kelvin (K)

ΔG = Change in the Gibbs free energy

ΔS = Change in entropy (at 298 K) as ΔS = Σ{S(Product (chemistry))} - Σ{S(Reagent)}

ΔH = Change in enthalpy (at 298 K) as ΔH = Σ{H(Product (chemistry))} - Σ{H(Reagent)}

A chemical reaction progresses only spontaneously when the Gibbs free energy decreases, in that case the ΔG is negative. In exergonic reactions the ΔG is negative and in endergonic reactions the ΔG is positive:

exergon

endergon

where:

equals the change in the Gibbs free energy after completion of a chemical reaction.

References

^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "exergonic (exoergic) reaction".

English Journal

Insights into Flavin-based Electron Bifurcation via the NADH- dependent Reduced Ferredoxin: NADP oxidoreductase Structure.

Demmer JK1, Huang H2, Wang S3, Demmer U1, Thauer RK4, Ermler U5.
The Journal of biological chemistry.J Biol Chem.2015 Jul 2. pii: jbc.M115.656520. [Epub ahead of print]
NADH-dependent reduced ferredoxin: NADP oxidoreductase (NfnAB) is found in the cytoplasm of various anaerobic bacteria and archaea. The enzyme reversibly catalyzes the endergonic reduction of ferredoxin with NADPH driven by the exergonic transhydrogenation from NADPH onto NAD+. Coupling is most prob
PMID 26139605

QM/MM modeling of the hydroxylation of the androstenedione substrate catalyzed by cytochrome P450 aromatase (CYP19A1).

Viciano I1, Castillo R1, Martí S1.
Journal of computational chemistry.J Comput Chem.2015 Jun 19. doi: 10.1002/jcc.23967. [Epub ahead of print]
CYP19A1 aromatase is a member of the Cytochrome P450 family of hemeproteins, and is the enzyme responsible for the final step of the androgens conversion into the corresponding estrogens, via a three-step oxidative process. For this reason, the inhibition of this enzyme plays an important role in th
PMID 26096372

Photoinduced Electron Transfer in DNA: Charge Shift Dynamics Between 8-Oxo-Guanine Anion and Adenine.

Zhang Y1, Dood J1, Beckstead AA1, Li XB2, Nguyen KV2, Burrows CJ2, Improta R3, Kohler B1.
The journal of physical chemistry. B.J Phys Chem B.2015 Jun 18;119(24):7491-502. doi: 10.1021/jp511220x. Epub 2015 Feb 23.
Femtosecond time-resolved IR spectroscopy is used to investigate the excited-state dynamics of a dinucleotide containing an 8-oxoguanine anion at the 5'-end and neutral adenine at the 3'-end. UV excitation of the dinucleotide transfers an electron from deprotonated 8-oxoguanine to its π-stacked nei
PMID 25660103