One-pot biotransformations gave oligo(gamma-L-Et-Glu) decorated with selected amine-functionalized end-groups at C-termini. Motivations for this work were to (i) control the end group structure of peptides synthesized by protease-catalyzed peptide synthesis and (ii) incorporate end-groups that can be used directly or after further modification as polymerizable entities. Papain, bromelain, alpha-chymotrypsin, Multifect P-3000, and Purafect prime 4000 L were used as catalysts for oligomerization of gamma-L-(Et)(2)-Glu in the presence of monofunctional amines. The series of amine nucleophiles (NH2-R, acyl acceptors) studied mimic phenylalanine in that they possess aromatic rings linked to amine groups by one or more methylenes. Generally, addition of increased quantities of NH2-R from 0 to 30, 50, and 70 mol % with respect to gamma-L-(Et)(2)-Glu results in decreased % yield, but increased mol %, of NH2-R end-capped oligo(gamma-L-Et-Glu)-NH-R (determined by NMR). Irrespective of the protease used, 2-thiophene methyl amine (TPMA) gave the highest fraction of oligo(gamma-L-Et-Glu)-NH-R chains. For example, using Multifect P-3000 and a feed ratio of TPMA- to gamma-L-(Et)(2)-Glu of 7:3, > 90 mol % of oligopeptides formed had TPMA C-terminal groups. With all five proteases studied herein, L-phenylalanine and L-histidine did not produce end-capped oligo(gamma-L-Et-Glu). In contrast, L-phenylamine analogs benzylamine (BzA) and L-phenylalaninol (F-OH), both of which lack the alpha-carboxyl group, gave substantial quantities of oligo(gamma-L-Et-Glu)-F-OH or -BzA chains. Hence, the results of this study prove that the promiscuity of proteases used herein can be exploited to create a diverse family of desired end-functionalized oligopeptides. MALDI-TOF spectra recorded of oligo(gamma-L-Et-Glu) with amine nucleophiles showed molecular ions that affirmed the formation of corresponding NH2-R functionalized oligo(gamma-L-Et-Glu).