Amino acid activation with adenosine 5'-phosphorimidazolide.

Amino acids are activated by reaction with adenosine 5'-phosphorimidazolide in aqueous imidazole buffers. If adenosine 5'-(O-methylphosphate), an analogue of the 3'-terminus of t-RNA is present, 2'(3')-O-aminoacyladenosine 5'-(O-methylphosphate) is formed. Fifteen percent of this compound accumulated at pH 5.8, but less was formed at higher pHs. The highest efficiency of utilization if ImpA attained in our experiments was about 24%. Analogous reactions occured with several other amino acids, including a number that have functional side-chains.