tRNA Activation

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•  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

tRNA activation