Cytidyl-3,5 -adenosine, reaction with

Further computational studies on adenines and adenosines concern the reaction mechanism of ribonuclease A with cytidyl-3,5 -adenosine [99BP697] and the molecular recognition of modified adenine nucleotides [99JMC5338]. 

In detail, the 3 -hydroxy-group of the ribose (in the terminal adenosine residue of each tRNA molecule) is acylated, enzymatically, by an activated form of that amino acid for which this tRNA is specific. Amide-ester exchange of these esters with peptidyl-tRNA on the ribosomes then occurs under the direction of mRNAs. In the latter step, the growing peptide is transferred from the tRNA bond on the donor site of the ribosomes to an aminoacyl-tRNA bond on the acceptor site of the same ribosome. This reaction is catalysed by the enzyme peptidyl transferase. The peptide, lengthened in this way, is then entirely shifted to the donor site with the help of a translocation enzyme. The next aminoacyl-tRNA then becomes bound to the vacant acceptor site, and the process is repeated. The terminal groups of the tRNAs are always —XCCA, where C is a cytidylic, and A an adenylic, acid residue. 

---