Application:
• tRNA-activating enzymes illustrate enzyme-substrate specificity and the role of phosphorylation
Each tRNA molecule binds with a specific amino acid in the cytoplasm in a reaction catalysed by a tRNA-activating enzyme
- Each amino acid is recognised by a specific enzyme (the enzyme may recognise multiple tRNA molecules due to degeneracy)
The binding of an amino acid to the tRNA acceptor stem occurs as a result of a two-step process:
- The enzyme binds ATP to the amino acid to form an amino acid–AMP complex linked by a high energy bond (PP released)
- The amino acid is then coupled to tRNA and the AMP is released – the tRNA molecule is now “charged” and ready for use
The function of the ATP (phosphorylation) is to create a high energy bond that is transferred to the tRNA molecule
- This stored energy will provide the majority of the energy required for peptide bond formation during translation
tRNA Activation
