The enzyme acetyl esterase from the flavedo of oranges (EC 3.1.1.6) ch
emo- and regioselectively removes acetyl groups from carbohydrates and
nucleosides. The chemoselective enzymatic liberation of the amino fun
ctions present in the nucleobases of O-acetylated nucleosides is achie
ved by penicillin G acylase (EC 3.5.1.11) mediated hydrolysis of the c
orresponding phenylacetamides.