Abstract
The primary amine initiated polymerization of N-carboxyanhydrides of amino acids (NCAs) has been proposed to proceed by two mechanisms: normal amine mechanism and activated monomer mechanism. Recently, Hadjichristidis <i>et al.</i> showed that high vacuum techniques could be employed to synthesize poly(amino acid)s initiated with primary amines exclusively <i>via</i> the normal amine mechanism. Unfortunately, no end group characterization was reported. Herein we report the end group characterization of the amine-initiated polymerization of the NCA of O-benzyl-L-tyrosine by MALDI-TOF MS and NALDI <sup>TM</sup>-TOF MS. We show that when synthesized <i>via</i> high vacuum techniques the reaction proceeds exclusively by the normal amine mechanism. The activated monomer mechanism is detected in samples prepared by less rigorous techniques.