PyrrolysineâÂÂtRNA<sup>Pyl</sup> ligase (, PylS, pyrrolysyl-tRNA synthetase) is an enzyme with systematic name L-pyrrolysine:tRNAPyl ligase (AMP-forming). This enzyme catalyses the following chemical reaction
This enzyme is specific for pyrrolysine as substrate as it cannot be replaced by lysine or any of the other natural amino acids.