Dipeptide synthesis catalyzed by aminoacyl-tRNA synthetases from Bacillus stearothermophilus.

A new approach to enzymatic peptide synthesis by using aminoacyl-tRNA synthetase (ARS) as a catalyst has been investigated. Four ARSs (AspRS, HisRS, LeuRS and TyrRS) have been purified from a thermophilic bacterium, Bacillus stearothermophilus. By using TyrRS as a catalyst, tyrosine and leucinamide were shown to be condensed in the presence of ATP to give tyrosylleucinamide. In this manner, all of the ARSs investigated catalyzed the peptide synthesis reactions. TyrRS did not have strict specificity for the amino acid derivatives used as substrates and even D-amino acids were incorporated into peptides fairly easily in this enzymatic reaction. Preparative scale synthesis of L-Tyr-L-LeuNH2 was carried out and from this the scope and limitation of this new enzymatic reaction as a tool to the peptide synthesis has been described.