BCH2011 Lecture Notes - Lecture 16: Nucleophile, Prokaryotic Large Ribosomal Subunit, Aminoacyl-Trna
Document Summary
For the synthesis of a polypeptide with a defined sequence, two fundamental chemical requirements must be met: The carboxyl group of each amino acid must be activated to facilitate formation of a peptide bond. A link must be established between each new amino acid and the information in the mrna that encodes it. Both of these requirements are met by attaching the amino acid to a trna in the first stage of protein synthesis. Attaching the right amino acid to the right trna is critical. This reaction takes place in the cytosol, not the ribosome. When attached to their amino acid (aminoacylated) the trnas are said to be charged". Aminoacyl-trna synthetases attach the correct amino acids to their trnas: During the first stage of protein synthesis, taking place in the cytosol, aminoacyl- trna synthetases esterify the 20 amino acids to their corresponding trnas. Each enzyme is specific for one amino acid and one or more corresponding trnas.