Activation of amino acids for protein synthesis | Crack PGIMER 22 MAY 2016

How many high-energy phosphate-bond equivalents are utilized in the process of activation of amino acids for protein synthesis?

a. Zero
b. One
c. Two
d. Three

The answer is C.

ATP is required for the esterification of amino acids to their corresponding tRNAs. This reaction is catalyzed by the class of enzymes known as aminoacyl-tRNA synthetases. Each one of these enzymes is specific for one tRNA and its corresponding amino acid. amino acid + tRNA + ATP → aminoacyl-tRNA + AMP + PPi As with most ATP hydrolysis r actions that release pyrophosphate, pyrophosphatase quickly hydrolyzes the product to Pi, which makes the reaction essentially irreversible. Since ATP is hydrolyzed to AMP and PPi during the reaction, by convention the equivalent of two high-energy phosphate bonds is utilized.