The formation of peptides from the 2'(3')-glycyl ester of a nucleotide

We have synthesized 2'(3')-O-(glycyl)-adenosine-5'-(O-methylphosphate), an analogue of the 3'-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5'-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine. The aminolysis of 2'(3')-O-(glycyl)-adenosine-5'-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.