Synthesis of cleavable peptides with authentic C-termini: an application for fully automated SPOT synthesis

A simple method for the synthesis of carboxyl-free peptides on cellulose membranes was improved and adapted for fully automated SPOT synthesis. Using 1,1′-carbonyl-di-imidazole (CDI) or 1,1′-carbonyl-di-(1,2,4-triazole) (CDT) as an activator within a defined period of time, we were able to reduce the formation of di- or oligomerization of the C-terminal amino acid. The soluble peptides are obtained in a purity range of 60-95% and could be used directly for different biological assays (e.g., CD8 T-cell epitope) that require authentic C-termini.

Direct coupling of CDI activated amino acids on cellulose membranes allows the synthesis of cleavable peptides with free C-termini in yields of at least 50 μg/cm2 which are enough for any biological assays.