Polypeptide synthesis using an expressed peptide as a building block for condensation with a peptide thioester: Application to the synthesis of phosphorylated p21Max protein(1-101)

An expressed peptide proved to be useful as a building block for the synthe sis of a polypeptide via the thioester method. A partially protected peptid e segment, for use as a C-terminal building block. could be prepared from a recombinant protein: its N-terminal amino acid residue was transaminated t o an alpha -oxoacyl group, the side-chain amino groups were then protected with t-butoxycarbonyl (Boc) groups, and, finally, the alpha -oxoacyl group was removed. On the other hand, an O-phosphoserine-containing peptide thioe ster was synthesized via a solid-phase method using Boc chemistry. These bu ilding blocks were then condensed in the presence of silver ions and an act ive ester component. During the condensation, epimerization at the condensa tion site could be suppressed by the use of N,N-dimthylformamide (DMF) as a solvent. Using this strategy, a phosphorylated partial peptide of the p21M ax protein, [Ser(PO3H2)(2.11)]-p21Max(1 - 101), was successfully synthesize d. Copyright (C) 2001 European Peptide Society and John Wiley & Sons. Ltd.