Access to the inaccessible sequence of cpn 60.1 (195-217) by temporary oxazolidine protection of selected amide bonds

The solid-phase peptide synthesis of a reportedly inaccessible peptide sequence of chaperonin 60.1 (195-219) is described using oxazolidine containing dipeptide building blocks ('pseudo-proline' dipeptide units). Two attempts at the synthesis of the chaperonin 60.1 sequence are outlined using one and two pseudo-proline units, respectively, and these results are compared with the outcome of an ordinary stepwise (double) coupling procedure. The only successful synthesis is that combining two pseudo-proline building blocks.