Peptide bond formationis exothermic or endothermic The formation of a peptide bond is a fundamental process in biochemistry, essential for building proteins and peptides.作者：R Tattersall·被引用次数：32—The largest contribution to the freeenergyvalue ofpeptide bond formationin aqueous solution is not from the actual forming of the CO - NH linkage, but is ... Understanding the peptide bond formation energy involves examining both the thermodynamic and kinetic aspects of this reaction. While the overall formation of a peptide bond from free amino acids in aqueous solution is thermodynamically unfavorable, requiring energy input, biological systems have evolved sophisticated mechanisms to overcome this barrier, making peptide formation energetically favorable under physiological conditions.
The direct reaction between the carboxyl group of one amino acid and the amino group of another to form a peptide bond, with the release of a water molecule (dehydration synthesis), is an endergonic reaction. This means it requires an input of energy to proceedPeptide bond hydrolyses parameters - Generic. The unfavorable enthalpy change and the need to overcome a significant activation energy present kinetic and thermodynamic hurdles. In aqueous solution, the energy barrier for uncatalyzed peptide bond formation can be substantial, often cited in the range of 96 to 105 KJ/mol for hydrolysis, indicating a high activation energy for the reverse reaction.Peptide bond In the gas phase, the free-energy barrier is even higher, underscoring the inherent difficulty of this reaction without assistance.作者：FS Brigiano·2022·被引用次数：26—By comparison, the glycine dimerization in bulk water yields an overall free-energybarrier of 195 kJ/mol, a reaction freeenergyof 62 kJ/mol ...
Organisms circumvent the unfavorable energetics of peptide bond formation by coupling it to highly exergonic reactions, primarily involving ATP (adenosine triphosphate)作者：AW Flegmann·1979·被引用次数：32—The thermodynamicenergybarrier topeptide bond formationwas found to decrease with increasing temperature: the standard freeenergyofpeptide bond.... The energy derived from ATP hydrolysis is conserved and utilized to activate amino acids, typically through the formation of aminoacyl-tRNAs. This activated intermediate then provides the necessary energy to drive the formation of the peptide bond on the ribosome. This process ensures that peptide bonds are formed efficiently and accurately during protein synthesis. While the direct formation of the C-N linkage is endergonic, the overall process facilitated by cellular machinery, including the ribosome and energy-carrying molecules, becomes energetically favorable.
It is crucial to distinguish between the thermodynamic favorability and kinetic stability of peptide bonds. Thermodynamically, the formation of a peptide bond from free amino acids and water is unfavorablePeptide bond formation is endergonic andhas a high activation energy, meaning there is both a thermodynamic and kinetic barrier to the formation of peptide .... However, once formed, the peptide bond itself is kinetically very stable. This means that the hydrolysis of a peptide bond (the reverse reaction, breaking the bond by adding water) requires a significant amount of activation energy to occur spontaneouslyThe formation of peptide bondsis energetically favorable under physiological conditions. The reaction is driven by the removal of water and the stabilization .... This kinetic stability is vital for the integrity of proteins within living organisms, preventing them from rapidly degrading. The high activation energy for hydrolysis ensures that proteins maintain their structure and function for extended periods.
Various studies have attempted to quantify the energy associated with peptide bond formation. For instance, the glycine dimerization in bulk water has been reported to have an overall free-energy barrier of approximately 195 kJ/mol and a reaction free energy of 62 kJ/mol, highlighting the unfavorable nature of the reaction in isolationPeptide bond hydrolyses parameters ; R. Bruce Martin,Free energies and equilibria of peptide bond hydrolysis and formation, Biopoly 45: 351–353, 1998 DOI: .... In specific contexts, such as the gas phase, the free-energy barrier can be extremely high. However, in aqueous solutions, the energy requirements are influenced by factors like protonation and the zwitterionic nature of amino acids. Some research indicates that for every n amino acids linked, there are n-1 peptide bonds, and the free energy of formation and hydrolysis are closely related.Free energies and equilibria of peptide bond hydrolysis ... Specific calculations for transition state activation energy have yielded values like 35.5 kcal/mol.Apeptideor amide (–CO–NH–)bondisformedby the linking of the carboxyl group of one amino acid with the amino group of another with the loss of a water ... Conversely, some sources mention that during the reaction, Gibbs energy is emitted in an amount of 8-16 kJ/mol, which might refer to specific activated intermediates or localized energy release within the complex cellular machinery rather than the direct uncatalyzed reaction.
In summary, peptide bond formation energy is a complex interplay of thermodynamic unfavorability and kinetic stability. While the direct chemical reaction between amino acids to form a peptide bond requires energy input and is thermodynamically unfavorable, biological systems, primarily through ATP-dependent activation and the machinery of the ribosome, effectively drive this process. The resulting peptide bond is kinetically robust, ensuring the stability of proteins.In the world of proteins, amino acids are linked together bypeptide bonds. A peptide is a short chain of amino acids containing between two and fifty amino acids. When two amino acids bind through a process called dehydration synthesis, apeptide bondisformed. Dehydration synthesis is a nucleophilic substitution ... Understanding these energetic principles is fundamental to comprehending protein synthesis and the stability of biological macromoleculesComputational study of peptide bond formation in the gas ....
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