The adapter function of the tRNA molecules require the charging of each specific tRNA with its specific amino acid. Since there is no affinity of nucleic acids for specific functional groups of amino acids, this recognition must be carried out by a protein molecule capable of recognizing both a specific tRNA molecule and a specific amino acid.
Activating enzymes called aminoacyl-tRNA synthetases couple each amino acid to its appropriate set of tRNA molecules. There are 20 synthetases for each of the 20 natural amino acids.
The reaction involves two steps :
The amino acid-tRNA bond is a high-energy linkage that easily reacts with the amino group of the next amino acid in a protein sequence to form a peptide bond during protein synthesis.
