Are PhAcOZ and Nsc suitable N alpha-protecting groups for protease-catalysed peptide synthesis?

Protecting groups are necessary chemical tools in peptide synthesis. In protease-catalysed peptide synthesis they exert influence both on enzyme-substrate binding and on solubility. In this study, we have investigated the usability of various PhAcOZ- and Nsc-protected amino acids for protease-catalysed peptide synthesis. PhAcOZ-protected peptides were obtained in high yields using papain and thermolysin. In contrast to this, Nsc, as a base-labile alpha-amino protecting group, is not suitable for biocatalytic synthesis under the conditions employed.