New enzymatic protecting group techniques for the construction of peptides and glycopeptides

The use of non-proteases for the selective removal of protecting groups from peptides and glycopeptides is described. The N-terminal deprotection of peptides can be achieved by the hydrolysis of the phenylacetyl (PhAc) amide blocking group catalyzed by penicillin G acylase. On the other hand, the lipase-mediated hydrolysis of n-heptyl (Hep) and 2-bromoethyl esters allows for the liberation of the C-terminal carboxy group. The selective C-terminal deprotection can be applied advantageously for the construction of acid- and base-sensitive polyfunctional O-glycopeptides. In all cases the enzymatic reactions are completely selective and proceed under mildest conditions (pH 7-8, r.t. to 37 degrees C) without damaging the various other functionalities present in the complex substrates.