Small-scale manual multiple peptide synthesis system. Application to phosphopeptide synthesis

A system for small-scale (ca. 10-50 mumol) manual multiple peptide synthesis assembled from commercially available solid-phase extraction apparatus is described. This system was used to prepare (on a 15 mumol scale) the five monophosphorylated isomers of the peptide ASTTVSKTE, a proteolytic fragment of the C-terminal region of rhodopsin. The peptides were assembled using serine or threonine active esters without hydroxyl protection at the positions of phosphorylation. Phosphate groups were introduced using postassembly phosphitylation/oxidation according to a published procedure [Andrews, D.M., Kitchin, J. & Seale, P.W. (1991) Int. J. Peptide Protein Res. 38, 469-475; Staerkaer, G., Jakobsen, M.H., Olsen, C.E. & Holm, A., Tetrahedron Lett. 32, 5389-5392; Perich, J.W. (1992) Int. J. Peptide Protein Res. 40 134-140]. The reported system provides a relatively inexpensive approach to multiple peptide synthesis, including synthesis of phosphopeptides, for laboratories whose synthesis requirements do not justify investment in an automated multiple peptide synthesis instrument.