A number of purine arabinosides containing chiral amino acid amides at the C6 position of the purine were synthesized using a transglycosylation reaction with recombinant nucleoside phosphorylases. Arsenolysis of 2-chloropurine ribosides with chiral amino acid amides at C6 was used for the enzymatic synthesis, and the reaction equilibrium shifted towards the synthesis of arabinonucleosides. The synthesized nucleosides were shown to be resistant to the action of adenosine deaminase. The antiproliferative activity of the synthesized nucleosides was studied on human acute myeloid leukemia cell line U937. Among all the compounds, the serine derivative exhibited an activity level (IC = 16 μM) close to that of Nelarabine (IC = 3 μM) and was evaluated as active.