Aminoacyl tRNA synthetases
aminoacyl trna synthetases
An aminoacyl tRNA synthetase ( aaRS ) is an enzyme that catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. In other words, aminoacyl tRNA synthetase simply attaches the appropriate, or 'cognate,' amino acid onto the corresponding tRNA. This is sometimes called 'charging' or 'loading' the tRNA with the amino acid. Once the tRNA is charged, a ribosome can transfer the amino acid from the tRNA onto a growing peptide, according to the genetic code.