Energy-rich bonds

High energy bonds, energy-rich bonds chemical bonds which release more than 25 kJ/mol on hydrolysis. They are usually esters (enol, thio and phosphate esters), acid anhydrides, or amidine phosphates. 

P a high energy or labile phosphate group. See High energy bonds. Energy-rich phosphates. 

The amino add is linked to its cognate tRNA with an energy-rich bond. 

Compounds of one acid with another are referred to as acid anhydrides. A particularly large amount of energy is required for the formation of an acid—anhydride bond. Phosphoric anhydride bonds therefore play a central role in the storage and release of chemical energy in the cell (see p. 122). Mixed anhydrides between carboxylic acids and phosphoric acid are also very important energy-rich metabolites in cellular metabolism. 

In standard conditions and at pH 7, the change in the chemical potential G (AG°, see p.l8) in this reaction amounts to -32 kj mol and it is therefore as high as the AG° of ATP hydrolysis (see p. 18). In addition to the energy-rich thioester bond, acetyl-CoA also has seven other hydrolyzable bonds with different degrees of stability. These bonds, and the fragments that arise when they are hydrolyzed, will be discussed here in sequence. 

When two phosphate residues bond, they do not form an ester, but an energy-rich phosphoric acid anhydride bond, as... 

After uptake by the cell, fatty acids are activated by conversion into their CoA derivatives—acyl CoA is formed. This uses up two energy-rich anhydride bonds of ATP per fatty acid (see p. 162). For channeling into the mitochondria, the acyl residues are first transferred to carnitine and then transported across the inner membrane as acyl carnitine (see B). 

Energy requirements in protein synthesis are high. Four energy-rich phosphoric acid anhydride bonds are hydrolyzed for each amino acid residue. Amino acid activation uses up two energy-rich bonds per amino acid (ATP AMP + PP see p. 248), and two GTPs are consumed per elongation cycle. In addition, initiation and termination each require one GTP per chain. 

Class 6 Ligases (join two molecules with hydrolysis of an energy-rich bond) Subclass 6.n What kind of bond is formed ... 

As a result, a rich catalytic combustor exhibits better light-off performance than a lean catalytic combustor. Veser et al. [136] also found that the ignition temperature correlates well with the C-H bond energy of the hydrocarbon, in line with the crucial role of activation of the first C-H bond proposed in the literature [140, 141[. 

ATP is an energy rich molecule because its triphosphate unit contains two phosphoanhydride bonds. A large amount of free energy is liberated when ATP is hydrolysed to ADP or AMP. 

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