The protein folding problem has been aptly termed the second genetic code, which stresses its fundamental importance to biology and the predictive power that would be available if the code were understood. It is believed that the first step in protein folding is the coiling of the randomly oriented linear polypeptide backbone into secondary structure (e.g. alpha-helices and beta- sheets), in which adjacent amino acid residues are locally ordered. Coiling of regions with defined secondary structure into a compact protein then follows. The long term objective of this project is the preparation and study of 'chimeric' polypeptides and proteins in which normal sequences of amino acids are linked to non-biological, rigid chemical spacers that can form strong hydrogen bonds to the adjacent peptide strands with the pattern of parallel or antiparallel beta-sheets. From the study of these composite molecules it is hoped that a set of predictive rules can be formulated that describe the conditions in which secondary sheet structure will invariably be formed. Ultimately, these rules are to be used to synthesize unnatural chimeric proteins that will fold predictably to form model structural proteins, model enzymes, and model binding and regulatory proteins. In the process of learning how to do this, it is likely that current models for the protein folding process can be tested, and the code itself can be elucidated. The specific immediate aims of this project include preparation of a series of template-linked peptides that fold predictably as determined by physical techniques such as circular dichroism and nuclear magnetic resonance. From these results, by a bootstrap process, more complex systems will be reduced to predictability.
