Organic reactions exergonic

BL has independently evolved many times some 30 different independent systems are still existent [7], Thus the responsible genes are unrelated in the various organisms, the enzymes show no homology to each other, and the substrates are chemically unrelated. There is, however, one common thread tying different systems at molecular level. All involve exergonic reactions of molecular... 

In living organisms, as in the mechanical example in Figure l-26a, an exergonic reaction can be coupled to an endergonic reaction to drive otherwise unfavorable... 

The recombination of free radicals can be highly exergonic, since in general a new bond is formed by the formerly non-bonding electrons. In the example of eqn. (4.59) the closed-shell molecule, N02, is then formed in an excited state which can decay through luminescence emission. Some organic free radicals show similar reactions but it must be stressed that in most cases the emission yields are low. 

The overall respiratory equation (3.40) represents the exergonic reaction, which energy in the form of highly active intermediate products is consumed by the organism. 

Fig. 1. Excited states of organic molecules generated directly and indirectly by an exergonic reaction...

Owing to their exergonic nature, Diels-Alder reactions are mostly run in an irreversible manner, resulting in kinetically determined regio- and stereo-chemistry. Therefore it is the successful control of its kinetics (featuring values of A// 16 to 18 kcal mol-1 and A5 = -30 to -40 kcal K-1 mol ) which is fundamental to the pivotal role of the Diels-Alder reaction in organic synthesis. 

In vitro. Reaction (18) proceeds irreversibly the analogous reaction in methionine biosynthesis is also highly exergonic [184]. In Methanosarcina strain G61 excess energy from Reaction (18) is conserved [195]. Working with washed everted vesicles of this organism Becker et al. [195] showed that the methyl transfer from CH3-H4 MPT to CoM generates a primary sodium motive force. 

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