A Synthetic Retrotransition (Backward Reading) Sequence of the Right-Handed Three-Helix Bundle Domain (10-53) of Protein A Shows Similarity in Confomation as Predicted by Computation

A recent computational analysis of retro-proteins (backward reading of native proteins) suggests that the retro-protein has a tendency to adopt a structure similar to that of the natural one, as demonstrated by a case study using a truncated version of the B-domain sequence (10-53) of protein A which forms a right-handed, three-helix bundle (Olszewski, K. A.; Kolinski, A.; Skolnick, J. Protein Eng. 1996, 9, 5−14). To test this hypothesis, both the natural 44 amino acid peptide and its retro-sequence have been synthesized by solid phase and purified to homogeneity. Circular dichroism studies indicate that both peptides adopt right-handed α-helical structures in the presence of trifluoroethanol. Though it is not clear if this tendency is general, this work does provide useful information for the study of protein folding.