Principles of Biochemistry, Volume 3 - A. Lehninger 1985

Molecular Mechanisms of Genetic Information Transfer
Protein Synthesis and Its Regulation
Energy is required to ensure the accuracy of protein synthesis

As we have already seen (Section 29.4), the enzymatic formation of each aminoacyl-tRNA from a free amino acid consumes two high-energy phosphate groups. Additional ATP molecules may be required at this stage to correct errors detected via the hydrolytic activity of aminoacyl-tRNA synthetase. Recall that one GTP molecule is cleaved to GDP and phosphate During the first stage of elongation, and another GTP molecule is hydrolyzed during translocation. Consequently, a total of at least four high-energy bonds are required for The formation of each peptide bond. This means that maintaining Protein Synthesis requires a substantial thermodynamic input, since the formation of a peptide bond consumes at least 7.3 ∙ 4 = 29.2 kcal of phosphate group energy, whereas the Standard Free energy of its Hydrolysis is only about – 5.0 kcal. Thus, the net Energy Expenditure for peptide bond synthesis is – 24.2 kcal/mol. Although such a high energy consumption may seem wasteful, it serves as a crucial factor ensuring the near-perfect fidelity of the biological Translation of mRNA Genetic information into the language of the Amino Acid Sequence of Proteins.