Aspartate—tRNA(Asn) ligase
Aspartate—tRNAAsn ligase is an enzyme with systematic name L-aspartate:tRNAAsx ligase . This enzyme catalyses the following chemical reaction
The 3 substrates of this enzyme are ATP, L-asparagine, and tRNAAsx, whereas its 3 products are AMP, diphosphate, and asparaginyl-tRNAAsx.
When this enzyme acts on tRNAAsp, it catalyses the same reaction as EC 6.1.1.12, aspartate---tRNA ligase. It has, however, diminished discrimination, so that it can also form aspartyl-tRNAAsn. This relaxation of specificity has been found to result from the absence of a loop in the tRNA that specifically recognizes the third position of the anticodon . This accounts for the ability of this enzyme in, for example, Thermus thermophilus, to recognize both tRNAAsp and tRNAAsn. The aspartyl-tRNAAsn is not used in protein synthesis until it is converted by EC 6.3.5.6, asparaginyl-tRNA synthase, into asparaginyl-tRNAAsn.
This enzyme belongs to the family of ligases, to be specific those forming carbon-oxygen bonds in aminoacyl-tRNA and related compounds. The systematic name of this enzyme class is L-asparaginyl:tRNAAsx ligase . This enzyme is also called nondiscriminating asparaginyl-tRNA synthetase. This enzyme participates in alanine and asparagine metabolism.