Final answer:
Class II aminoacyl-tRNA synthetases (aaRS) are responsible for the shifting of the amino acid from the 2' OH to the 3' OH position on the tRNA molecule during protein translation.
Step-by-step explanation:
The class of aminoacyl-tRNA synthetases (aaRS) that involves a shifting of the amino acid from the 2' OH to the 3' position is Class II aaRS. These enzymes catalyze the attachment of amino acids to their corresponding tRNAs, a crucial step in the translation of genetic information into proteins.
In Class II aaRS, such as LysRS, PheRS, HisRS, SerRS, and AspRS, the amino acid initially attaches to the 2' OH of the ribose sugar of the tRNA's adenosine residue at the 3' end. Subsequently, in some instances, it may shift to the 3' OH, thereby completing the aminoacylation process. It is also noted that some Class II enzymes, like PheRS, display characteristics atypical of their class, such as acylating in the Class I mode (2').